Design of a potent, soluble glucokinase activator with increased pharmacokinetic half-life

The continued optimization of a series of glucokinase activators is described, including attempts to understand the interplay between molecular structure and the composite parameter of unbound clearance. These studies resulted in the discovery of a new scaffold for glucokinase activators and further exploration of this scaffold led to the identification of GKA60. GKA60 maintains an excellent balance of potency and physical properties whilst possessing a significantly different, but complimentary, pre-clinical pharmacokinetic profile compared with the previously disclosed compound GKA50.     

Isolation and introgression in the Intermountain West: contrasting gene genealogies reveal the complex biogeographic history of the American pika (Ochotona princeps)

Aim We studied the history of colonization, diversification and introgression among major phylogroups in the American pika, Ochotona princeps (Lagomorpha), using comparative and statistical phylogeographic methods. Our goal was to understand how Pleistocene climatic fluctuations have shaped the distribution of diversity at mitochondrial DNA (mtDNA) and nuclear DNA (nDNA) loci in this alpine specialist. Location North America’s Intermountain West. Methods We accumulated mtDNA sequence data (c. 560–1700 bp) from 232 pikas representing 64 localities, and sequenced two nuclear introns (mast cell growth factor, c. 550 bp, n = 148; protein kinase C iota, c. 660 bp, n = 139) from a subset of individuals. To determine the distribution of major mtDNA lineages, we conducted a phylogenetic analysis on the mtDNA sequence data, and we calculated divergence times among the lineages using a Bayesian Markov chain Monte Carlo approach. Relationships among nuclear alleles were explored with minimum spanning networks. Finally, we conducted coalescent simulations of alternative models of population history to test for congruence between nDNA and mtDNA responses to Pleistocene glacial cycles. Results We found that: (1) all individuals could be assigned to one of five allopatric mtDNA lineages; (2) lineages are associated with separate mountain provinces; (3) lineages originated from at least two rounds of differentiation; (4) nDNA and mtDNA markers exhibited overall phylogeographic congruence; and (5) introgression among phylogroups has occurred at nuclear loci since their initial isolation. Main conclusions Pika populations associated with different mountain systems have followed separate but not completely independent evolutionary trajectories through multiple glacial cycles. Range expansion associated with climate cooling (i.e. glaciations) promoted genetic admixture among populations within mountain ranges. It also permitted periodic contact and introgression between phylogroups associated with different mountain systems, the record of which is retained at nDNA but not mtDNA loci. Evidence for different histories at nuclear and mtDNA loci (i.e. periodic introgression versus deep isolation, respectively) emphasizes the importance of multilocus perspectives for reconstructing complete population histories.     

3-([3-125I]iodo-4-hydroxyphenyl)propionyl carbohydrazide,a new radioiodination reagent for ultrasensitive detection and determination of periodate-oxidized nucleoside derivatives and other carbonyl compounds

A new radioiodination reagent for the identification and quantitation of periodate-oxidized ribonucleosides was developed. The reagent, 3-([3-¹²⁵I]iodo-4-hydroxyphenyl)propionyl carbohydrazide, was prepared by radioiodination of 3-(4-hydroxyphenyl)propionic acid N-hydroxysuccinimide ester in the presence of chloramine T, followed by reduction of the latter with sodium arsenite and treatment of the radioiodinated ester with an excess of carbohydrazide. The reagent reacted quantitatively with periodate-oxidized nucleosides to form ¹²⁵I-labeled morpholine derivatives which were separated by thin-layer chromatography and quantitated by liquid scintillation counting. The reagent was found to react also with other carbonyl compounds and thus may find more general application in the qualitative and quantitative ultramicroanalysis of aldehydes and ketones.     

Mouse LSECtin as a model for a human Ebola virus receptor

The biochemical properties of mouse LSECtin, a glycan-binding receptor that is a member of the C-type lectin family found on sinusoidal endothelial cells, have been investigated. The C-type carbohydrate-recognition domain of mouse LSECtin, expressed in bacteria, has been used in solid-phase binding assays, and a tetramerized form has been used to probe a glycan array. In spite of sequence differences near the glycan-binding sites, the mouse receptor closely mimics the properties of the human receptor, showing high affinity binding to glycans bearing terminal GlcNAcβ1-2Man motifs. Site-directed mutagenesis has been used to confirm that residues near the binding site that differ between the human and the mouse proteins do not affect this binding specificity. Mouse and human LSECtin have been shown to bind Ebola virus glycoprotein with equivalent affinities, and the GlcNAcβ1-2Man disaccharide has been demonstrated to be an effective inhibitor of this interaction. These studies provide a basis for using mouse LSECtin, and knockout mice lacking this receptor, to model the biological properties of the human receptor.     

NMR Structures of α-Proteobacterial ATPase-Regulating ζ-Subunits

NMR structures of ζ-subunits, which are recently discovered α-proteobacterial F₁F₀-ATPase-regulatory proteins representing a Pfam protein family of 246 sequences from 219 species (PF07345), exhibit a four-helix bundle, which is different from all other known F₁F₀-ATPase inhibitors. Chemical shift mapping reveals a conserved ADP/ATP binding site in ζ-subunit, which mediates long-range conformational changes related to function, as revealed by the structure of the Paracoccus denitrificans ζ-subunit in complex with ADP. These structural data suggest a new mechanism of F₁F₀-ATPase regulation in α-proteobacteria.     

Analysis of greenhouse gas emissions related to aluminium transport applications

Background, aim and scope

Climate change is a subject of growing global concern. Based on International Energy Agency (IEA 2004) research, about 19% of the greenhouse gas emissions from fuel combustion are generated by the transportation sector, and its share is likely to grow. Significant increases in the vehicles fleets are expected in particular in China, India, the Middle East and Latin America. As a result, reducing vehicle fuel consumption is most essential for the future. The reduction of the vehicle weight, the introduction of improved engine technologies, lower air friction, better lubricants, etc. are established methods of improving fuel efficiency, reducing energy consumption and greenhouse gas emissions. Continued progress will be required along all these fronts with light-weighting being one of the most promising options for the global transport sector. This paper quantifies greenhouse gas savings realised from light-weighting cars with aluminium based on life cycle assessment methodology. The study uses a pragmatic approach to assess mass reduction by comparing specific examples of components meeting identical performance criteria. The four examples presented in this analysis come from practical applications of aluminium. For each case study, the vehicle manufacturer has supplied the respective masses of the aluminium and the alternative component.

Material and methods

A full life cycle assessment with regards to greenhouse gas emissions and savings has been carried out for different aluminium applications in cars as compared to the same applications in steel or cast iron. The case studies reference real cases, where aluminium is actually used in series production. The studies are based on a greenhouse gas lifecycle model, which has been developed following the ISO standard 14040 framework. For each component, sensitivity analysis is applied to determine the impact of lifetime driving distance, driving characteristics (impact of air friction) and recycling rate.

Results

Life cycle results show that in automotive applications, each kilogram of aluminium replacing mild steel, cast iron or high strength steel saves, depending on the specific case (bumper and motor block of a compact car, front hood of a large family car, body-in white of a luxury car), between 13 and 20 kg of greenhouse gas emissions.

Discussion

The performed sensitivity analysis finds that even with ‘worst case’ scenarios savings are still significant.

Conclusions

The results not only demonstrate significant benefits of aluminium with regard to greenhouse gas savings but also show that these are very sensitive to variations of the recycling rate, the life-time driving distance and the driving behaviour.

Recommendations and perspectives

Good care is needed to gather life-cycle data and to make informed estimates, where no data are available. Furthermore, greenhouse gas savings for additional components should be calculated using this life cycle model to sustain the findings.

     

miR‐29a suppresses tristetraprolin,which is a regulator of epithelial polarity and metastasis

Several microRNAs (miRNAs) have recently been described as crucial regulators of epithelial‐to‐mesenchymal transition (EMT) and metastasis. By comparing the expression profiles of miRNAs, we found upregulation of miR‐29a in mesenchymal, metastatic RasXT cells relative to epithelial EpRas cells. Overexpression of miR‐29a suppressed the expression of tristetraprolin (TTP), a protein involved in the degradation of messenger RNAs with AU‐rich 3′‐untranslated regions, and led to EMT and metastasis in cooperation with oncogenic Ras signalling. We also observed enhanced miR‐29a and reduced TTP levels in breast cancer patient samples, indicating relevance for human disease. Previously, miR‐29 family members were shown to have tumour‐suppressive effects in haematopoietic, cholangiocytic and lung tumours. Therefore, miRNAs can act as either oncogenes or tumour suppressors, depending on the context.     

Differential expression of genes participating in cardiomyocyte electrophysiological remodeling via membrane ionic mechanisms and Ca2+-handling in human heart failure

Molecular and Cellular Biochemistry - Excitation–contraction coupling in normal cardiac function is performed with well balanced and coordinated functioning but with complex dynamic...     

Delayed Phenotypic Expression of Growth Hormone Transgenesis during Early Ontogeny in Atlantic Salmon (Salmo salar)?

Should growth hormone (GH) transgenic Atlantic salmon escape, there may be the potential for ecological and genetic impacts on wild populations. This study compared the developmental rate and respiratory metabolism of GH transgenic and non-transgenic full sibling Atlantic salmon during early ontogeny; a life history period of intense selection that may provide critical insight into the fitness consequences of escaped transgenics. Transgenesis did not affect the routine oxygen consumption of eyed embryos, newly hatched larvae or first-feeding juveniles. Moreover, the timing of early life history events was similar, with transgenic fish hatching less than one day earlier, on average, than their non-transgenic siblings. As the start of exogenous feeding neared, however, transgenic fish were somewhat developmentally behind, having more unused yolk and being slightly smaller than their non-transgenic siblings. Although such differences were found between transgenic and non-transgenic siblings, family differences were more important in explaining phenotypic variation. These findings suggest that biologically significant differences in fitness-related traits between GH transgenic and non-transgenic Atlantic salmon were less than family differences during the earliest life stages. The implications of these results are discussed in light of the ecological risk assessment of genetically modified animals.