Discovery of novel biaryl sulfonamide based Mcl-1 inhibitors

Mcl-1 is an anti-apoptotic protein overexpressed in hematological malignancies and several human solid tumors. Small molecule inhibition of Mcl-1 would offer an effective therapy to Mcl-1 mediated resistance. Subsequently, it has been the target of extensive research in the pharmaceutical industry. The discovery of a novel class of Mcl-1 small molecule inhibitors is described beginning with a simple biaryl sulfonamide hit derived from a high through put screen. A medicinal chemistry effort aided by SBDD generated compounds capable of disrupting the Mcl-1/Bid protein-protein interaction in vitro. The crystal structure of the Mcl-1 bound ligand represents a unique binding mode to the BH3 binding pocket where binding affinity is achieved, in part, through a sulfonamide oxygen/Arg263 interaction. The work highlights the some of the key challenges in designing effective protein-protein inhibitors for the Bcl-2 class of proteins.     

Asymmetric Cell Division in Normal and Malignant Hematopoietic Precursor Cells

Hematopoietic precursors have long been postulated to divide in an asymmetric manner. In this issue of Cell Stem Cell, Wu et al. (2007) provide evidence for the existence of asymmetric cell division and its possible molecular control in normal and transformed blood precursor cells.     

Interstitial Fluid Colloid Osmotic Pressure in Healthy Children

Objective

The colloid osmotic pressure (COP) of plasma and interstitial fluid play important roles in transvascular fluid exchange. COP values for monitoring fluid balance in healthy and sick children have not been established. This study set out to determine reference values of COP in healthy children.

Materials and Methods

COP in plasma and interstitial fluid harvested from nylon wicks was measured in 99 healthy children from 2 to 10 years of age. Nylon wicks were implanted subcutaneously in arm and leg while patients were sedated and intubated during a minor surgical procedure. COP was analyzed in a colloid osmometer designed for small fluid samples.

Results

The mean plasma COP in all children was 25.6 ± 3.3 mmHg. Arbitrary division of children in four different age groups, showed no significant difference in plasma or interstitial fluid COP values for patients less than 8 years, whereas patients of 8-10 years had significant higher COP both in plasma and interstitial fluid. There were no gender difference or correlation between COP in interstitial fluid sampled from arm and leg and no significant effect on interstitial COP of gravity. Prolonged implantation time did not affect interstitial COP.

Conclusion

Plasma and interstitial COP in healthy children are comparable to adults and COP seems to increase with age in children. Knowledge of the interaction between colloid osmotic forces can be helpful in diseases associated with fluid imbalance and may be crucial in deciding different fluid treatment options.

Trial Registration

ClinicalTrials.gov NCT01044641     

Characterization of the insertase BamA in three different membrane mimetics by solution NMR spectroscopy

The insertase BamA is the central protein of the Bam complex responsible for outer membrane protein biogenesis in Gram-negative bacteria. BamA features a 16-stranded transmembrane β-barrel and five periplasmic POTRA domains, with a total molecular weight of 88 kDa. Whereas the structure of BamA has recently been determined by X-ray crystallography, its functional mechanism is not well understood. This mechanism comprises the insertion of substrates from a dynamic, chaperone-bound state into the bacterial outer membrane, and NMR spectroscopy is thus a method of choice for its elucidation. Here, we report solution NMR studies of different BamA constructs in three different membrane mimetic systems: LDAO micelles, DMPC:DiC₇PC bicelles and MSP1D1:DMPC nanodiscs. The impact of biochemical parameters on the spectral quality was investigated, including the total protein concentration and the detergent:protein ratio. The barrel of BamA is folded in micelles, bicelles and nanodiscs, but the N-terminal POTRA5 domain is flexibly unfolded in the absence of POTRA4. Measurements of backbone dynamics show that the variable insertion region of BamA, located in the extracellular lid loop L6, features high local flexibility. Our work establishes biochemical preparation schemes for BamA, which will serve as a platform for structural and functional studies of BamA and its role within the Bam complex by solution NMR spectroscopy.     

Potential age of aquatic Oligochaeta

The maximum lifetime of species with exclusively sexual reproduction covers 5–15 years or even more in aquaria, although most specimens die consecutively earlier. The zooids of paratomic species live some weeks or months, their clones usually less than a year, rarely for some years. In the species with facultative architomy (fragmentation) the clonal age also exceeds that of the individual, both lasting for several years. The actual lifetime of worms in nature may be shorter than in cultures.     

Morphology and development of the cranium of Felis silvestris f. catus Linné 1758--a contribution to the comparative anatomy of the Carnivora. III: Ear region and occipital region

In Felis, the otic region of younger embryonic stages up to Felis 1 is characterized by extremely medial extended cochleae, compressing the basal plate to a slender trabeculum. As a result of a quite strong rostrad convergence of the long axis of the ear capsules, the Commissura praefacialis fuses with the Commissura orbitoparietalis laterally. Until now, this has been found in whales only. Continuing embryogenesis towards Felis 2, the cochlea moves laterally and slightly ventrally, so the angle of convergence between the whole Capsula otica and the skull base decreases. The problem of interpreting these positional changes of the Capsula otica during phylogenesis and ontogenesis is discussed in detail. Up to recent literature, there is a discussion about homology of the Foramen perilymphaticum and allied structures in reptiles referring to the openings in the Capsula otica in mammals. Configuration of these structures in fissiped carnivores and the appearance of a "limitating membrane" in Felis 2, gives reason for a new discussion of these problems. Composition of the Bulla tympani is a very important feature for investigation of phylogeny and systematics in fissiped carnivores. In Felis 2, there appears a caudal entotympanic, consisting of young cartilaginous tissue. The development of the caudal entotympanic has impact on 2 structures in the occipital region: The Lamina alaris and the Processus paracondyloideus. Felis 1 shows a distinct Lamina alaris and a short Processus paracondyloideus. With Felis 2, either element is reduced largely, probably to the extent as the caudal entotympanic develops.