Febrile seizures: traffic slows in the heat

Febrile seizures, which occur in young children, have long been known to have a major inherited component. Mutations in some genes that encode sodium channel and GABA(A) receptor subunits have been found in a few families affected by febrile seizures. These mutations account only for a minority of cases, and much remains to be learnt about the molecular architecture of febrile seizures. A rare inherited cause--a mutation in the GABA(A) receptor subunit GABRG2 gene--has been recently shown to cause a temperature-dependent intracellular trafficking defect. This is an important step in unravelling the molecular pathogenesis of this common childhood disorder.     

Comparison of a Salmonella typhimurium proteome defined by shotgun proteomics directly on an LTQ-FT and by proteome pre-fractionation on an LCQ-DUO.

Shotgun proteomics is rapidly becoming one of the most efficient and popular tools to examine protein expression in cells. Numerous laboratories now have a wide array of low- and high-performance mass spectrometry instrumentation necessary to complete proteome-wide projects. Often these laboratories have time and financial constraints that prohibit all projects from being conducted on high-performance state-of-the-art mass spectrometers. Here, we compare shotgun proteomic results using a direct 'lyse, digest and analyse' approach on a high-performance mass spectrometer (i.e. the LTQ-FT) with the results from a much lower-performance instrument (i.e. the LCQ-DUO) where, for the latter, various traditional protein pre-fractionation steps and gas-phase fractionation were used to increase the proteome coverage. Our results demonstrate that shotgun proteomic analyses conducted on the lower-performance LCQ-DUO mass spectrometer could adequately characterize a PhoP constitutive strain of Salmonella typhimurium if proteome pre-fractionation steps and gas-phase fractionation were included.     

Novel IL10 gene family associations with systemic juvenile idiopathic arthritis

Juvenile idiopathic arthritis (JIA) is the most common cause of chronic childhood disability and encompasses a number of disease subgroups. In this study we have focused on systemic JIA (sJIA), which accounts for approximately 11% of UK JIA cases. This study reports the investigation of three members of the IL10 gene family as candidate susceptibility loci in children with sJIA. DNA from 473 unaffected controls and 172 patients with sJIA was genotyped for a single nucleotide polymorphism (SNP) in IL19 and IL20 and two SNPs in IL10. We examined evidence for association of the four SNPs by single marker and haplotype analysis. Significant differences in allele frequency were observed between cases and controls, for both IL10-1082 (p = 0.031) and IL20-468 (p = 0.028). Furthermore, examination of the haplotypes of IL10-1082 and IL20-468 revealed greater evidence for association (global p = 0.0006). This study demonstrates a significant increased prevalence of the low expressing IL10-1082 genotype in patients with sJIA. In addition, we show a separate association with an IL20 polymorphism, and the IL10-1082A/IL20-468T haplotype. The two marker 'A-T' haplotype confers an odds ratio of 2.24 for sJIA. This positive association suggests an important role for these cytokines in sJIA pathogenesis.     

Euler buckling-induced folding and rotation of red blood cells in an optical trap

We investigate the physics of an optically driven micromotor of biological origin. When a single, live red blood cell (RBC) is placed in an optical trap, the normal biconcave disc shape of the cell is observed to fold into a rod-like shape. If the trapping laser beam is circularly polarized, the folded RBC rotates. A model based on geometric considerations, using the concept of buckling instabilities, captures the folding phenomenon; the rotation of the cell is rationalized using the Poincaré sphere. Our model predicts that (i) at a critical power of the trapping laser beam the RBC shape undergoes large fluctuations, and (ii) the torque that is generated is proportional to the power of the laser beam. These predictions are verified experimentally. We suggest a possible mechanism for the emergence of birefringent properties in the RBC in the folded state.     

Presentation of RGDS epitopes on self-assembled nanofibers of branched peptide amphiphiles

Branched peptide amphiphile (PA) molecules bearing biological epitopes were designed and synthesized using orthogonal protecting group chemistry on amine groups at lysine residues. These molecules self-assemble into high-aspect-ratio cylindrical nanofibers, and their branched architecture enhances accessibility of epitopes for protein binding and also allows the presentation of more than one epitope in a single molecule. The RGDS cell adhesion epitope was used as a model bioactive signal on PA molecules for potential biomedical applications. Aggregation of the branched PA molecules into nanofibers was demonstrated by TEM and through shifts in the protonation profiles of peripheral amines. These systems also formed self-supporting gels in the presence of physiological fluids and other biologically relevant macromolecules such as synovial fluid and DNA, an important property for their potential use in medicine. Fluorescence anisotropy measurements on the PAs with tryptophan residues were performed to examine the effect of branching on packing and mobility of the peptides in the self-assembled nanofibers. The mobility of tryptophan residues was observed to be restricted upon packing of PA molecules into nanofibers. However, relative to linear analogues, branched molecules retain more mobility in the supramolecular aggregates.     

Does thermal history affect metabolic plasticity?: a study in three Phyllotis species along an altitudinal gradient

(1) The aim of this study was to understand the effects of thermal history in metabolic features such as maximum (MMR) and basal (BMR) metabolic rates, as well as in metabolic plasticity, considered as the total variation of MMR and BMR during the acclimation period. (2) We studied three species of the genus Phyllotis, from different thermal environments, in an altitudinal gradient from sea level to 3800m.a.s.l. Animals were acclimated to contrasting temperatures of 5 and 30 degrees C. To determine the metabolic flexibility, MMR was measured at intervals of 6 days during the acclimation period, while BMR values were obtained at the end of acclimations. Aerobic scope and the rates of change of MMR were estimated in all populations. (3) High- and low-altitude rodents did not show differences in BMR. However, both upper and lower limits of MMR, as well as aerobic scope, were significantly different between high- and low-altitude species, indicating similar ranges of metabolic plasticity. On the other hand, the rates of change of MMR were similar in all populations. (4) Our results indicate that thermal history has a profound effect on the individuals' thermogenic capacity, probably in both phylogenetic and ontogenetic levels. Low-altitude species could not increase MMR to the same levels as high-altitude species, while the later were unable to decrease MMR to achieve the values of the low-altitude species.     

The synthesis and biological evaluation of a series of potent dual inhibitors of farnesyl and geranyl-Geranyl protein transferases

We have prepared a series of potent, dual inhibitors of the prenyl transferases farnesyl protein transferase (FPTase) and geranyl-geranyl protein transferase I (GGPTase). The compounds were shown to possess potent activity against both enzymes in cell culture. Mechanistic analysis has shown that the compounds are CAAX competitive for FPTase inhibition but geranyl-geranyl pyrophosphate (GGPP) competitive for GGPTase inhibiton.     

The role of gamma interferon in antimicrobial immunity

Gamma interferon (IFN-gamma) is an important cytokine in the host defense against infection by viral and microbial pathogens. IFN-gamma induces a variety of physiologically significant responses that contribute to immunity. Treatment of animal cells with IFN-gamma or infection with viral or microbial pathogens leads to changes in the level of expression of several target genes as revealed by DNA microarray analyses. The signaling pathways leading to the induction of IFN-gamma-regulated gene products and, in some cases, their biochemical functions have been defined in exquisite detail. Studies of transgenic mutant mice deficient in proteins of the IFN-gamma response pathway firmly establish the importance of IFN-gamma in immunity.     

Gene expression profiling of breast carcinomas using nylon DNA arrays

Clinically very heterogeneous, breast cancer prognosis and treatment response are difficult to predict with the current prognostic histoclinical parameters. Mammary oncogenesis remains poorly understood. DNA array technology allows the simultaneous analysis of the mRNA expression levels of thousands of genes in biological samples. Applied to breast tumours, expression profiles will boost our knowledge of oncogenesis, will offer new potential therapeutic targets and new prognostic and predictive markers. Today, the most accessible approach for academic research teams is that of Nylon DNA arrays with radioactive detection, which in addition allows profiling of small clinical samples.     

Interferon signatures in immune disorders and disease

The interferon (IFN) family and the type-I IFNs specifically have an important and well-characterized role in antiviral defence, immune modulation and cell-cycle control and are regularly applied in the clinical context. Advances in high-content technologies have facilitated an enhanced understanding of the global IFN response capable of being induced. Recent application of these technologies is improving our understanding of the specificity and subtleties associated with this response. This review considers our current understanding of the temporal gene profile induced through IFN stimulation across a diversity of disease conditions including autoimmune diseases, bacterial and viral infections. Understanding these signatures, the disease-specific differences and the biological effects induced has the potential to facilitate IFN-driven therapeutic development.