Chaos in a Damped Power System

The analytical investigation of a damped power system has been made based on Holmes and Marsden's theorems. The condition for the occurrence of chaotic motions in the system is that the damping factor has to possess negative values. The numerical simulation results concur very well with theoretical predictions.     

Accelerated evolution in the reactive centre regions of serine protease inhibitors

The serine protease inhibitors (serpins) are a family of proteins that function to control the action of serine proteases in many diverse physiological processes. The functional region or reactive centre of these inhibitors is near the C-terminal end and is an exposed site that acts as a bait for the appropriate serine protease to recognize and covalently bind. The specificity of the inhibitor is determined, at least in part, by a single amino acid that resides in this region at the P1 position. We show here that following a gene duplication event the reactive centres of three related rodent protease inhibitors have diverged from each other at unprecedented rates. This has resulted in proteins with different predicted specificities and we postulate that these changes were fixed by positive darwinian selection and that the most likely selective forces are extrinsic proteases, namely those used by parasites to facilitate their spread throughout the host.     

Human homologs of a Drosophila Enhancer of split gene product define a novel family of nuclear proteins.

Notch and the m9/10 gene (groucho) of the Enhancer of split (E(spI)) complex are members of the "Notch group" of genes, which is required for a variety of cell fate choices in Drosophila. We have characterized human cDNA clones encoding a family of proteins, designated TLE, that are homologous to the E(spI) m9/10 gene product, as well as a novel Notch-related protein. The TLE genes are differentially expressed and encode nuclear proteins, consistent with the presence of sequence motifs associated with nuclear functions. The structural redundancy implied by the existence of more than one TLE and Notch-homologous gene may be a feature of the human counterparts of the developmentally important Drosophila Notch group genes.     

Interaction between ERAP1 and HLA-B27 in ankylosing spondylitis implicates peptide handling in the mechanism for HLA-B27 in disease susceptibility

Ankylosing spondylitis is a common form of inflammatory arthritis predominantly affecting the spine and pelvis that occurs in approximately 5 out of 1,000 adults of European descent. Here we report the identification of three variants in the RUNX3, LTBR-TNFRSF1A and IL12B regions convincingly associated with ankylosing spondylitis (P < 5 × 10(-8) in the combined discovery and replication datasets) and a further four loci at PTGER4, TBKBP1, ANTXR2 and CARD9 that show strong association across all our datasets (P < 5 × 10(-6) overall, with support in each of the three datasets studied). We also show that polymorphisms of ERAP1, which encodes an endoplasmic reticulum aminopeptidase involved in peptide trimming before HLA class I presentation, only affect ankylosing spondylitis risk in HLA-B27-positive individuals. These findings provide strong evidence that HLA-B27 operates in ankylosing spondylitis through a mechanism involving aberrant processing of antigenic peptides.     

A Mal functional variant is associated with protection against invasive pneumococcal disease, bacteremia, malaria and tuberculosis

Toll-like receptors (TLRs) and members of their signaling pathway are important in the initiation of the innate immune response to a wide variety of pathogens. The adaptor protein Mal (also known as TIRAP), encoded by TIRAP (MIM 606252), mediates downstream signaling of TLR2 and TLR4 (refs. 4-6). We report a case-control study of 6,106 individuals from the UK, Vietnam and several African countries with invasive pneumococcal disease, bacteremia, malaria and tuberculosis. We genotyped 33 SNPs, including rs8177374, which encodes a leucine substitution at Ser180 of Mal. We found that heterozygous carriage of this variant associated independently with all four infectious diseases in the different study populations. Combining the study groups, we found substantial support for a protective effect of S180L heterozygosity against these infectious diseases (N = 6,106; overall P = 9.6 x 10(-8)). We found that the Mal S180L variant attenuated TLR2 signal transduction.