Lutein effect on retina and hippocampus of diabetic mice

Oxidative stress markers and functional tests were studied to confirm early biochemical and functional changes in retina and hippocampus of diabetic mice. The effects of lutein treatment were also tested. Mice were induced diabetic by alloxan injection and divided into subgroups: control, control+lutein, diabetic, diabetic+lutein, diabetic+insulin, and diabetic+insulin+lutein. Treatments started on Day 4 after alloxan injection and animals were sacrificed on Day 14. Malondialdehyde and glutathione concentrations and glutathione peroxidase activity were measured as oxidative stress markers. The following functional tests for retina and hippocampus were performed: electroretinogram and Morris water maze test. NFkappaB activity was also measured. Oxidative stress and NFkappaB activity increase in the retina and hippocampus after 15 days of diabetes. Impairment of the electroretinogram and a correlation between latencies of the water maze test and glycated hemoglobin (HbA1c) levels were observed. Lutein prevented all these changes even under hyperglycemic conditions. Retina appears to be affected earlier than hippocampus by diabetes-induced oxidative stress. Although a proper glycemic control is desirable in preventing the development of diabetic complications, it is not sufficient to prevent them completely. Lutein could be an appropriate coadjuvant treatment for the changes observed in this study.     

Saccharomyces cerevisiae strain expressing a plant fatty acid desaturase produces polyunsaturated fatty acids and is susceptible to oxidative stress induced by lipid peroxidation

Although oxygen is essential for aerobic organisms, it also forms potentially harmful reactive oxygen species. For its simplicity, easy manipulation, and cultivation conditions, yeast is used as an attractive model in oxidative stress research. However, lack of polyunsaturated fatty acids in yeast membranes makes yeast unsuitable for research in the field of lipid peroxidation. Therefore, we have constructed a yeast strain expressing a Delta12 desaturase gene from the tropical rubber tree, Hevea brasiliensis. This yeast strain expresses the heterologous desaturase in an active form and, consequently, produces Delta9/Delta12 polyunsaturated fatty acids under inducing conditions. The functional expression of the heterologous desaturase did not affect cellular morphology or growth, indicating no general adverse effect on cellular physiology. However, the presence of polyunsaturated fatty acids changed the yeast's sensitivity to oxidative stress induced by addition of paraquat, tert-butylhydroperoxide, and hydrogen peroxide. This difference in sensitivity to the latter was followed by the formation of 4-hydroxy-2-nonenal, one of the end products of linoleic fatty acid peroxidation, which is known to play a role in cell growth control and signaling. Here we show that this yeast strain conditionally expressing the Delta12 desaturase gene provides a novel and well-defined eukaryotic model in lipid peroxidation research. Its potential to investigate the molecular basis of responses to oxidative stress, in particular the involvement of reactive aldehydes derived from fatty acid peroxidation, especially 4-hydroxy-2-nonenal, will be addressed.     

Modulators of the human CCR5 receptor. Part 3: SAR of substituted 1-[3-(4-methanesulfonylphenyl)-3-phenylpropyl]-piperidinyl phenylacetamides

SAR and PK studies led to the identification of N-(1-{(3R)-3-(3,5-difluorophenyl)-3-[4-methanesulfonylphenyl] propyl}piperidin-4-yl)-N-ethyl-2-[4-methanesulfonylphenyl]acetamide as a highly potent and selective ligand for the human CCR5 chemokine receptor with good oral pharmacokinetic properties.     

Inhibitors of epidermal growth factor receptor tyrosine kinase: optimisation of potency and in vivo pharmacokinetics

The structure-activity and structure-property relationships of anilinoquinazoline inhibitors of EGFR were investigated. Strategies to lower volume of distribution and shorten half-life through structure and pKa modulation are discussed.     

The crystal structure of human receptor protein tyrosine phosphatase kappa phosphatase domain 1

The receptor-type protein tyrosine phosphatases (RPTPs) are integral membrane proteins composed of extracellular adhesion molecule-like domains, a single transmembrane domain, and a cytoplasmic domain. The cytoplasmic domain consists of tandem PTP domains, of which the D1 domain is enzymatically active. RPTPkappa is a member of the R2A/IIb subfamily of RPTPs along with RPTPmu, RPTPrho, and RPTPlambda. Here, we have determined the crystal structure of catalytically active, monomeric D1 domain of RPTPkappa at 1.9 A. Structural comparison with other PTP family members indicates an overall classical PTP architecture of twisted mixed beta-sheets flanked by alpha-helices, in which the catalytically important WPD loop is in an unhindered open conformation. Though the residues forming the dimeric interface in the RPTPmu structure are all conserved, they are not involved in the protein-protein interaction in RPTPkappa. The N-terminal beta-strand, formed by betax association with betay, is conserved only in RPTPs but not in cytosolic PTPs, and this feature is conserved in the RPTPkappa structure forming a beta-strand. Analytical ultracentrifugation studies show that the presence of reducing agents and higher ionic strength are necessary to maintain RPTPkappa as a monomer. In this family the crystal structure of catalytically active RPTPmu D1 was solved as a dimer, but the dimerization was proposed to be a consequence of crystallization since the protein was monomeric in solution. In agreement, we show that RPTPkappa is monomeric in solution and crystal structure.     

Directed evolution of human T cell receptor CDR2 residues by phage display dramatically enhances affinity for cognate peptide-MHC without increasing apparent cross-reactivity

The mammalian alpha/beta T cell receptor (TCR) repertoire plays a pivotal role in adaptive immunity by recognizing short, processed, peptide antigens bound in the context of a highly diverse family of cell-surface major histocompatibility complexes (pMHCs). Despite the extensive TCR-MHC interaction surface, peptide-independent cross-reactivity of native TCRs is generally avoided through cell-mediated selection of molecules with low inherent affinity for MHC. Here we show that, contrary to expectations, the germ line-encoded complementarity determining regions (CDRs) of human TCRs, namely the CDR2s, which appear to contact only the MHC surface and not the bound peptide, can be engineered to yield soluble low nanomolar affinity ligands that retain a surprisingly high degree of specificity for the cognate pMHC target. Structural investigation of one such CDR2 mutant implicates shape complementarity of the mutant CDR2 contact interfaces as being a key determinant of the increased affinity. Our results suggest that manipulation of germ line CDR2 loops may provide a useful route to the production of high-affinity TCRs with therapeutic and diagnostic potential.     

Responding to environmental change: plastic responses vary little in a synchronous breeder

The impact of environmental change on animal populations is strongly influenced by the ability of individuals to plastically adjust key life-history events. There is therefore considerable interest in establishing the degree of plasticity in traits and how selection acts on plasticity in natural populations. Breeding time is a key life-history trait that affects fitness and recent studies have found that females vary significantly in their breeding time-environment relationships, with selection often favouring individuals exhibiting stronger plastic responses. In contrast, here, we show that although breeding time in the common guillemot, Uria aalge, is highly plastic at the population level in response to a large-scale environmental cue (the North Atlantic Oscillation, NAO), there is very little between-individual variation-most individuals respond to this climate cue very similarly. We demonstrate strong stabilizing selection against individuals who deviate from the average population-level response to NAO. This species differs significantly from those previously studied in being a colonial breeder, in which reproductive synchrony has a substantial impact on fitness; we suggest that counter selection imposed by a need for synchrony could limit individuals in their response and potential for directional selection to act. This demonstrates the importance of considering the relative costs and benefits of highly plastic responses in assessing the likely response of a population to the environmental change.     

The absence of sharks from abyssal regions of the world's oceans

The oceanic abyss (depths greater than 3000 m), one of the largest environments on the planet, is characterized by absence of solar light, high pressures and remoteness from surface food supply necessitating special molecular, physiological, behavioural and ecological adaptations of organisms that live there. Sampling by trawl, baited hooks and cameras we show that the Chondrichthyes (sharks, rays and chimaeras) are absent from, or very rare in this region. Analysis of a global data set shows a trend of rapid disappearance of chondrichthyan species with depth when compared with bony fishes. Sharks, apparently well adapted to life at high pressures are conspicuous on slopes down to 2000 m including scavenging at food falls such as dead whales. We propose that they are excluded from the abyss by high-energy demand, including an oil-rich liver for buoyancy, which cannot be sustained in extreme oligotrophic conditions. Sharks are apparently confined to ca 30% of the total ocean and distribution of many species is fragmented around sea mounts, ocean ridges and ocean margins. All populations are therefore within reach of human fisheries, and there is no hidden reserve of chondrichthyan biomass or biodiversity in the deep sea. Sharks may be more vulnerable to over-exploitation than previously thought.     

Synthesis and biological evaluation of fused thio- and selenopyrans as new indolocarbazole analogues with aryl hydrocarbon receptor affinity

A series of thio- and selenopyrans having two fused indole units, structurally related to indolocarbazoles, have been prepared and evaluated for aryl hydrocarbon receptor (AhR) affinity, leading to the identification of several new significant AhR ligands. In particular, the parent thiopyrano[2,3-b:6,5-b′]diindole and its derivative having a methyl group in the central ring, as well as the two corresponding selenopyrans, displayed the highest potencies of the compounds tested.