A False-Positive Screening Hit in Fragment-Based Lead Discovery: Watch out for the Red Herring.

With the rising popularity of fragment-based approaches in drug development, more and more attention has to be devoted to the detection of false-positive screening results. In particular, the small size and low affinity of fragments drives screening techniques to their limit. The pursuit of a false-positive hit can cause significant loss of time and resources.

Active Site Mapping of an Aspartic Protease by Multiple Fragment Crystal Structures: Versatile Warheads To Address a Catalytic Dyad.

Crystallography is frequently used as follow-up method to validate hits identified by biophysical screening cascades. The capacity of crystallography to directly screen fragment libraries is often underestimated, due to its supposed low-throughput and need for high-quality crystals. We applied crystallographic fragment screening to map the protein-binding site of the aspartic protease endothiapepsin by individual soaking experiments.

Experimental Active-Site Mapping by Fragments: Hot Spots Remote from the Catalytic Center of Endothiapepsin.

Successful optimization of a given lead scaffold requires thorough binding-site mapping of the target protein particular in regions remote from the catalytic center where high conservation across protein families is given. We screened a 361-entry fragment library for binding to the aspartic protease endothiapepsin by crystallography. This enzyme is frequently used as a surrogate for the design of renin and β-secretase inhibitors.

High-Throughput Crystallography: Reliable and Efficient Identification of Fragment Hits.

Today the identification of lead structures for drug development often starts from small fragment-like molecules raising the chances to find compounds that successfully pass clinical trials. At the heart of the screening for fragments binding to a specific target, crystallography delivers structural information essential for subsequent drug design. While it is common to search for bound ligands in electron densities calculated directly after an initial refinement cycle, we raise the important question whether this strategy is viable for fragments characterized by low affinities.

Fragment Linking and Optimization of Inhibitors of the Aspartic Protease Endothiapepsin: Fragment-Based Drug Design Facilitated by Dynamic Combinatorial Chemistry.

Fragment-based drug design (FBDD) affords active compounds for biological targets. While there are numerous reports on FBDD by fragment growing/optimization, fragment linking has rarely been reported. Dynamic combinatorial chemistry (DCC) has become a powerful hit-identification strategy for biological targets.

Six Biophysical Screening Methods Miss a Large Proportion of Crystallographically Discovered Fragment Hits: A Case Study.

Fragment-based lead discovery (FBLD) has become a pillar in drug development. Typical applications of this method comprise at least two biophysical screens as prefilter and a follow-up crystallographic experiment on a subset of fragments. Clearly, structural information is pivotal in FBLD, but a key question is whether such a screening cascade strategy will retrieve the majority of fragment-bound structures.

Structure-Based Optimization of Inhibitors of the Aspartic Protease Endothiapepsin.

Aspartic proteases are a class of enzymes that play a causative role in numerous diseases such as malaria (plasmepsins), Alzheimer's disease (β-secretase), fungal infections (secreted aspartic proteases), and hypertension (renin). We have chosen endothiapepsin as a model enzyme of this class of enzymes, for the design, preparation and biochemical evaluation of a new series of inhibitors of endothiapepsin. Here, we have optimized a hit, identified by de novo structure-based drug design (SBDD) and DCC, by using structure-based design approaches focusing on the optimization of an amide-π interaction.

One Question, Multiple Answers: Biochemical and Biophysical Screening Methods Retrieve Deviating Fragment Hit Lists.

Fragment-based lead discovery is gaining momentum in drug development. Typically, a hierarchical cascade of several screening techniques is consulted to identify fragment hits which are then analyzed by crystallography. Because crystal structures with bound fragments are essential for the subsequent hit-to-lead-to-drug optimization, the screening process should distinguish reliably between binders and non-binders.

Visualization of Tissue Removal using Focus + Context Techniques.

Current dataset visualizations have limited capability of allowing users to remove only small regions of the dataset and inspect the remaining volume. We have developed a new visualization based on the focus + context paradigm to provide users with a 3D volume or 2D slice rendering of regions that are marked as arbitrary-shaped focus and shown as drilled-out. A novel way of computing whether the rays traversing the dataset fall within the drilled-out region results in an accurate rendering of the sculpted context dataset.

Structure-based design of inhibitors of the aspartic protease endothiapepsin by exploiting dynamic combinatorial chemistry.

Structure-based design (SBD) can be used for the design and/or optimization of new inhibitors for a biological target. Whereas de novo SBD is rarely used, most reports on SBD are dealing with the optimization of an initial hit. Dynamic combinatorial chemistry (DCC) has emerged as a powerful strategy to identify bioactive ligands given that it enables the target to direct the synthesis of its strongest binder.

Generalized temporal focus + context framework for improved medical data exploration.

Physicians use slices and 3D volume visualizations to place a diagnosis, establish a treatment plan and as a guide during surgical procedures. There is an observed difference in 2D and 3D visualization objectives of the various groups of specialists. We describe a generalized temporal focus + context framework that unifies different widely used and novel visualization methods.

[Viskaldix in the treatment of arterial hypertension].

Viskaldix, a combination of Pindolol (Visken)--10 mg with Clopamide--5 mg, was administered to 15 patients with arterial hypertension. The follow up of the patients was according to a previous plan, the preparation administered according, to a schedule. In the determination of the stage of the disease, consideration was mainly given to the values of the diastolic pressure, measured in a lying position.

[Diagnostic difficulties in symptomatic erythrocytosis developing in congenital heart defects].

A case with symptomatic erythrocytosis in a female patient with ductus Botalli persistens is described, diagnosed and treated as erythremia vera. The heart disease advanced with no manifestations, with no complaints until the age of 30, whereon it was manifested with certain complaints and objective findings. The inadequate and difficult assessment of some of the clinical, hematological and other data as X-ray of the heart and ECG, contributed to the improper diagnosis.