Characterization of proteins that interact with the GTP-bound form of the regulatory GTPase Ran in Arabidopsis

Ran, a small soluble GTP-binding protein, has been shown to be essential for the nuclear translocation of proteins and it is also thought to be involved in regulating cell cycle progression in mammalian and yeast cells. Genes encoding Ran-like proteins have been isolated from different higher plant species. Overexpression of plant Ran cDNAs, similarly to their mammalian/yeast homologues, suppresses the phenotype of the pim46-1 cell cycle mutant in yeast cells. The mammalian/yeast Ran proteins have been shown to interact with a battery of Ran-binding proteins, including the guanidine nucleotide exchange factor RCC1, the GTPase-activating Ran-GAP, nucleoporins and other Ran-binding proteins (RanBPs) specific for Ran-GTP. Here, the characterization of the first Ran-binding proteins from higher plants is reported. The yeast two-hybrid system was used to isolate cDNA clones encoding proteins of approximately 28 kDa (At-RanBP1a, At-RanBP1b) that interact with the GTP-bound forms of the Ran1, Ran2 and Ran3 proteins of Arabidopsis thaliana . The deduced amino acid sequences of the At-RanBP1s display high similarity (60%) to mammalian/yeast RanBP1 proteins and contain the characteristic Ran-binding domains. Furthermore, interaction of the plant Ran and RanBP1 proteins, is shown to require the acidic C-terminal domain (-DEDDDL) of Ran proteins in addition to the presence of an intact Ran-binding domain. In whole cell extracts, the GST-RanBP1a fusion protein binds specifically to GTP-Ran and will not interact with Rab/Ypt-type small GTP-binding proteins. Finally, in good agreement with their proposed biological function, the At-Ran and the At-RanBP genes are expressed coordinately and show the highest level of expression in meristematic tissues.     

Etiology, risks factors, therapy of nosocomial cerebrovascular infections

Nosocomial cerebrovacsular infections are substantial cause of mortality and morbidity in patients after neurosurgery. Risk factors, etiology, treatment strategies and outcome of nosocomial meningitis and brain abscess are briefly reviewed.     

Bacterial meningitis after sinusitis and otitis media: ear, nose, throat infections are still the commonest risk factors for the community acquired meningitis

We investigated how many cases of bacterial meningitis in our national survey were associated with sinusitis or otitis media. Among 372 cases of bacterial meningitis within our nationwide 17 years survey, 201 cases were community acquired (CBM) and in 40 (20%) otitis media or sinusitis acuta/chronica were reported 1-5 weeks before onset of CBM. Diabetes mellitus (20% vs. 7.5%, p=0.01), alcohol abuse (35% vs. 15.4%, p=0.003) and trauma (30% vs. 14.9%, p=0.02) were significantly associated with CBM after ENT infections. Concerning etiology, CBM after sinusitis/otitis was insignificantly associated with pneumococcal etiology (50% vs. 33.8 %, NS) and significantly associated with other (L. monocytogenes, Str. agalactiae) bacterial agents (9.9 % vs. 25 %, p=0.008) . However those significant differences for new ENT related CBM had no impact on mortality (12.4 % vs. 5%, NS), failure after initial antibiotics (10 % vs. 9.5%, NS) and neurologic sequellae (12.5 % vs. 15.4 %, NS).     

Bacterial meningitis after craniocerebral trauma in the community

Craniocerebral trauma is one of major risk factors for development of meningitis. We reviewed 30 cases of bacterial meningitis occurring in community after craniocerebral trauma. Alcohol abuse was significant risk factor occurring in trauma patients with meningitis present in 50% in our cohort (p=0.0001). The most common pathogen in posttraumatic meningitis was Str. pneumoniae (90% vs. 33.8%, p=0.0001). However mortality was very low, only 5% probably because of early diagnosis and treatment of patients at risk for bacterial meningitis but neurologic sequellea were significantly more common (p=0.00001) in patients after craniocerebral trauma.     

Predictors of inferior outcome in community acquired bacterial meningitis

The aim of this study was to assess mortality and sequellae within cases from Nationwide survey of community acquired meningitis and identify risk factors for inferior outcome. Risk factors such as underlying disease (diabetes mellitus, cancer, trauma, neonatal age, splenectomy, alcoholism, sepsis, other infections), etiology, clinical symptoms and outcome (death, improvement and cured after modifications of ATB therapy, cured without change of therapy, cured with neurologic sequellae) were recorded and analysed with univariate analysis (chi2 or t test for trends, CDC Atlanta 2004). Analysing risk factors for inferior outcome (death or cured with neurologic sequellae), we compared patients who died or survived with neurologic sequellae to all patients with community acquired bacterial meningitis. Univariate analysis showed that trauma (p<0.05), alcohol abuse (p<0.05), diabetes, S. aureus (p<0.05) and gram-negative etiology (A. baumannii, Ps. aeruginosa or Enterobacteriaceae) (36% vs. 11,9%, p<0.05) were predicting inferior outcome. Analysing risk factors for treatment failure (death or failed but cured after change of antibiotic treatment) prior sepsis (34.1% vs. 13.9%, p<0.01) and gram-negative etiology (25% vs. 11.9%, p<0.02) were statistically significant predictors of treatment failure. Neisseria meningitis had less failures (p<0.05). Concerning infection associated mortality again diabetes mellitus (p<0.05), alcoholism (p<0.05) staphylococcal and gram-negative etiology (p<0.05) were significant predictors of death. N. meningitis had surprisingly less treatment failures (appropriate and rapid initial therapy). Neurologic sequellae were more common in patients with alcohol abuse (p<0.05), craniocerbral trauma (p<0.05) and less common in meningitis with pneumococcal etiology (p<0.05).     

Development of lipid-core-peptide (LCP) based vaccines for the prevention of group A streptococcal (GAS) infection

Traditional vaccines consisting of whole attenuated micro-organisms, or microbial components administered with adjuvant, have been demonstrated as one of the most cost-effective and successful public health interventions. Their use in large scale immunisation programs has lead to the eradication of smallpox, reduced morbidity and mortality from many once common diseases, and reduced strain on health services. However, problems associated with these vaccines including risk of infection, adverse effects, and the requirement for refrigerated transport and storage have led to the investigation of alternative vaccine technologies. Peptide vaccines, consisting of either whole proteins or individual peptide epitopes, have attracted much interest, as they may be synthesised to high purity and induce highly specific immune responses. However, problems including difficulties stimulating long lasting immunity, and population MHC diversity necessitating multiepitopic vaccines and/or HLA tissue typing of patients complicate their development. Furthermore, toxic adjuvants are necessary to render them immunogenic, and as such non-toxic human-compatible adjuvants need to be developed. Lipidation has been demonstrated as a human compatible adjuvant for peptide vaccines. The lipid-core-peptide (LCP) system, incorporating lipid adjuvant, carrier, and peptide epitopes, exhibits promise as a lipid-based peptide vaccine adjuvant. The studies reviewed herein investigate the use of the LCP system for developing vaccines to protect against group A streptococcal (GAS) infection. The studies demonstrate that LCP-based GAS vaccines are capable of inducing high-titres of antigen specific IgG antibodies. Furthermore, mice immunised with an LCP-based GAS vaccine were protected against challenge with 8830 strain GAS.     

Isometric gene tree reconciliation revisited

Background

Isometric gene tree reconciliation is a gene tree/species tree reconciliation problem where both the gene tree and the species tree include branch lengths, and these branch lengths must be respected by the reconciliation. The problem was introduced by Ma et al. in 2008 in the context of reconstructing evolutionary histories of genomes in the infinite sites model.

Results

In this paper, we show that the original algorithm by Ma et al. is incorrect, and we propose a modified algorithm that addresses the problems that we discovered. We have also improved the running time from \(O(N^2)\) to \(O(N\log N)\), where N is the total number of nodes in the two input trees. Finally, we examine two new variants of the problem: reconciliation of two unrooted trees and scaling of branch lengths of the gene tree during reconciliation of two rooted trees.

Conclusions

We provide several new algorithms for isometric reconciliation of trees. Some questions in this area remain open; most importantly extensions of the problem allowing for imprecise estimates of branch lengths.

     

Effects of neuropeptide Y on behavior and noradrenaline level in the brain

The administration of neuropeptide Y in lower doses (1 and 100 ng/rat) into the lateral ventricle of the brain gave rise to the inhibition of locomotor activity, weakening of the orienting-exploratory behaviour, increase in the period of rest in animals. Feeding and drinking behaviour after the administration of neuropeptide was not observed. Alterations of behaviour in rats were followed by a dose-depended increase in noradrenaline in hypothalamus. No changes were observed in the content of noradrenaline in the frontal cortex and septum. Some variations in the level of noradrenaline were found in amygdala and hippocamp. It may be assumed that behavioural effects, aroused by the central administration of neuropeptide Y, is connected with the activation of catecholaminergic systems of hypothalamus.