Structure and function of a cyanophage-encoded peptide deformylase

Bacteriophages encode auxiliary metabolic genes that support more efficient phage replication. For example, cyanophages carry several genes to maintain host photosynthesis throughout infection, shuttling the energy and reducing power generated away from carbon fixation and into anabolic pathways. Photodamage to the D1/D2 proteins at the core of photosystem II necessitates their continual replacement. Synthesis of functional proteins in bacteria requires co-translational removal of the N-terminal formyl group by a peptide deformylase (PDF). Analysis of marine metagenomes to identify phage-encoded homologs of known metabolic genes found that marine phages carry PDF genes, suggesting that their expression during infection might benefit phage replication. We identified a PDF homolog in the genome of Synechococcus cyanophage S-SSM7. Sequence analysis confirmed that it possesses the three absolutely conserved motifs that form the active site in PDF metalloproteases. Phylogenetic analysis placed it within the Type 1B subclass, most closely related to the Arabidopsis chloroplast PDF, but lacking the C-terminal α-helix characteristic of that group. PDF proteins from this phage and from Synechococcus elongatus were expressed and characterized. The phage PDF is the more active enzyme and deformylates the N-terminal tetrapeptides from D1 proteins more efficiently than those from ribosomal proteins. Solution of the X-ray/crystal structures of those two PDFs to 1.95 Å resolution revealed active sites identical to that of the Type 1B Arabidopsis chloroplast PDF. Taken together, these findings show that many cyanophages encode a PDF with a D1 substrate preference that adds to the repertoire of genes used by phages to maintain photosynthetic activities.     

Potential association of obesity with IL6 G-174C polymorphism and TTV infections

Polymorphisms in IL6, ACE and ATR genes are associated with obesity. Torque Teno virus (TTV) seems to be able to interfere with production of some proinflammatory cytokines associated with obesity and related phenotypes. The aim of this study was to test the potential association between obesity, TTV infection and the IL6 G-174C (rs1800795), ACE I/D (rs4646994), AT1R A1166C (rs5186) polymorphisms. The polymorphisms and the presence of TTV were detected in blood samples from 150 obese and 150 normal-weight, healthy subjects using PCR based methods. IL6-174 CC genotype was more frequent in all obese patients (P=0.02) and in patients without TTV infections (P=0.03) than in controls. Obese women had more frequent TTV infections compared with normal-weight women (P=0.046). Obese subjects, regardless of gender (women P=0.03, men P=0.04), and healthy normal-weight men (P<0.01) carriers of AT1R C allele had higher triglycerides levels compared with non-carriers. The frequency of TTV in the control group (70.67%) was similar to data reported in other populations. The present study indicated that IL6-174 CC genotype and TTV infections in women could be associated with the common form of obesity.     

Measuring Frailty in HIV-infected Individuals. Identification of Frail Patients is the First Step to Amelioration and Reversal of Frailty

A simple, validated protocol consisting of a battery of tests is available to identify elderly patients with frailty syndrome. This syndrome of decreased reserve and resistance to stressors increases in incidence with increasing age. In the elderly, frailty may pursue a step-wise loss of function from non-frail to pre-frail to frail. We studied frailty in HIV-infected patients and found that ~20% are frail using the Fried phenotype using stringent criteria developed for the elderly^1,2. In HIV infection the syndrome occurs at a younger age.HIV patients were checked for 1) unintentional weight loss; 2) slowness as determined by walking speed; 3) weakness as measured by a grip dynamometer; 4) exhaustion by responses to a depression scale; and 5) low physical activity was determined by assessing kilocalories expended in a week''s time. Pre-frailty was present with any two of five criteria and frailty was present if any three of the five criteria were abnormal.The tests take approximately 10-15 min to complete and they can be performed by medical assistants during routine clinic visits. Test results are scored by referring to standard tables. Understanding which of the five components contribute to frailty in an individual patient can allow the clinician to address relevant underlying problems, many of which are not evident in routine HIV clinic visits.     

Microbial activity in drinking water-associated biofilms

Microbial biofilms from surfaces in contact with water may play a beneficial role in drinking water treatment as biological filters. However, detrimental effects such as biofouling (i.e., biocorrosion and water quality deterioration) may also occur. In this study microbiological processes and factors influencing the activity of bacteria in biofilms were investigated by conventional cultivation methods. The presence of bacteria belonging to different ecophysiological groups was assessed during drinking water treatment, in biofilms developed on concrete, steel and sand surfaces. Influences of the treatment process, type of immersed material and physico-chemical characteristics of raw/bulk water and biofilms upon the dynamics of bacterial communities were evaluated. Results revealed intense microbial activity in biofilms occurring in the drinking water treatment plant of Cluj. Ammonification, iron reduction and manganese oxidation were found to be the predominant processes. Multiple significant correlations were established between the evolution of biofilm bacteria and the physico-chemical parameters of raw/ bulk water. The type of immersed material proved to have no significant influence upon the evolution of microbial communities, but the treatment stage, suggesting that the processes applied restrict microbial growth not only in bulk fluid but in biofilms, too.     

Permissive Summer Temperatures of the 2010 European West Nile Fever Upsurge

Background

In the summer of 2010, Europe experienced outbreaks of West Nile Fever (WNF) in humans, which was preceded by hot spells. The objective of this study was to identify potential drivers of these outbreaks, such as spring and summer temperatures, relative humidity (RH), and precipitation.

Methods

Pearson and lag correlations, binary and multinomial logistic regressions were used to assess the relationship between the climatic parameters and these outbreaks.

Results

For human morbidity, significant (<0.05) positive correlations were observed between a number of WNF cases and temperature, with a geographic latitude gradient: northern (“colder”) countries displayed strong correlations with a lag of up to four weeks, in contrast to southern (“warmer”) countries, where the response was immediate. The correlations with RH were weaker, while the association with precipitation was not consistent. Horse morbidity started three weeks later than in humans where integrated surveillance was conducted, and no significant associations with temperature or RH were found for lags of 0 to 4 weeks.

Conclusions

Significant temperature deviations during summer months might be considered environmental precursors of WNF outbreaks in humans, particularly at more northern latitudes. These insights can guide vector abatement strategies by health practitioners in areas at risk for persistent transmission cycles.     

Glucan particles for selective delivery of siRNA to phagocytic cells in mice

Phagocytic macrophages and dendritic cells are desirable targets for potential RNAi (RNA interference) therapeutics because they often mediate pathogenic inflammation and autoimmune responses. We recently engineered a complex 5 component glucan-based encapsulation system for siRNA (small interfering RNA) delivery to phagocytes. In experiments designed to simplify this original formulation, we discovered that the amphipathic peptide Endo-Porter forms stable nanocomplexes with siRNA that can mediate potent gene silencing in multiple cell types. In order to restrict such gene silencing to phagocytes, a method was developed to entrap siRNA-Endo-Porter complexes in glucan shells of 2-4 μm diameter in the absence of other components. The resulting glucan particles containing fluorescently labelled siRNA were readily internalized by macrophages, but not other cell types, and released the labelled siRNA into the macrophage cytoplasm. Intraperitoneal administration of such glucan particles containing siRNA-Endo-Porter complexes to mice caused gene silencing specifically in macrophages that internalized the particles. These results from the present study indicate that specific targeting to phagocytes is mediated by the glucan, whereas Endo-Porter peptide serves both to anchor siRNA within glucan particles and to catalyse escape of siRNA from phagosomes. Thus we have developed a simplified siRNA delivery system that effectively and specifically targets phagocytes in culture or in intact mice.     

Palatal and mandibular tori in a Romanian removable denture-wearing population

doi:10.1111/j.1741‐2358.2009.00318.x
Palatal and mandibular tori in a Romanian removable denture‐wearing population Objective: To establish the prevalence of palatal tori (TP) and mandibular tori (TM) in a Romanian denture‐wearing population in order to see how or if tori influenced the denture design or the treatment planning. Background data: There are no available data regarding tori in an elderly Romanian population and its implication for treatment planning. It could be considered a local factor influencing the quality of prosthetic treatment. Material and method: Tori prevalence was investigated in 251 patients, with an average age of 62 years. A statistical analysis was made, using odds ratio (OR) for the distribution related to gender and the Chi‐squared test for the differences in prevalence related to age groups. Treatment planning difficulties because of presence of tori were recorded. Results: Frequency of TP was significantly higher in both genders (OR = 2.0661 and p = 0.0446) and non‐significant frequency for distribution between genders for TM (OR = 0.9421 and p = 0.8273). The differences in age groups showed both tori types have a variable prevalence related to age. The most frequent location for TP was found in the posterior one‐third and two‐thirds of the palate and for TM in the canine and first premolar area presenting with different sizes. Conclusions: Tori prevalence in our study group is high and is significantly related to age (p < 0.05) having a peak at over 60 years. The preferential site of TP in the posterior palatal area and this location has an impact on decision making in treatment planning for the upper denture.     

Class IA phosphoinositide 3-kinase β and δ regulate neutrophil oxidase activation in response to Aspergillus fumigatus hyphae

An effective immune response to the ubiquitous fungus Aspergillus fumigatus is dependent upon production of reactive oxygen species (ROS) by the NADPH oxidase. This is evidenced by the acute sensitivity of oxidase-deficient humans and mice to invasive aspergillosis. Neutrophils are recruited to the lungs shortly postinfection and respond by phagocytosing conidia and mediating extracellular killing of germinated hyphae in a ROS-dependent manner. However, the signaling mechanisms regulating the generation of ROS in response to hyphae are poorly understood. PI3Ks are important regulators of numerous cellular processes, with much recent work describing unique roles for the different class I PI3K isoforms. We showed by live-cell imaging that the lipid products of class I PI3Ks accumulated at the hyphal-bound neutrophil plasma membrane. Further, we used pharmacological and genetic approaches to demonstrate essential, but overlapping, roles for PI3Kβ and PI3Kδ in the ROS and spreading responses of murine neutrophils to Aspergillus hyphae. Hyphal-induced ROS responses were substantially inhibited by deletion of the common β2-integrin subunit CD18, with only a minor, redundant role for Dectin-1. However, addition of soluble algal glucans plus the genetic deletion of CD18 were required to significantly inhibit activation of the PI3K-effector protein kinase B. Hyphal ROS responses were also totally dependent on the presence of Syk, but not its ITAM-containing adaptor proteins FcRγ or DAP12, and the Vav family of Rac-guanine nucleotide exchange factors. These results start to define the signaling network controlling neutrophil ROS responses to A. fumigatus hyphae.     

The structure-antituberculosis activity relationships study in a series of 5-aryl-2-thio-1,3,4-oxadiazole derivatives

A series of 82 5-aryl-2-thio-1,3,4-oxadiazole derivatives were screened for their anti-mycobacterial activities against Mycobacterium tuberculosis H37Rv. The synthesized compounds 30-37 appeared to be the most active derivatives exhibiting more than 90% inhibition of mycobacterial growth at 12.5 μg/mL. Structure-activity relationships study was performed for the given series by using the electronic-topological method combined with neural networks (ETM-NN). A system for the anti-mycobacterial activity prediction was developed as the result of training associative neural network (ASNN) with weights calculated from projections of a compound and each pharmacophoric fragment found on the elements of the Kohonen's self-organizing maps (SOMs). From the detailed analysis of all compounds under study, the necessary requirements for a compound to possess antituberculosis activity have been formulated. The analysis has shown that any requirement's violation for a molecule implies a considerable decrease or even complete loss of its activity. Molecular docking studies of the compounds allowed shedding light on the binding mode of these novel anti-mycobacterial inhibitors.     

pH - Specific synthesis, spectroscopic, and structural characterization of an assembly of species between Co(II) and N,N-bis(phosphonomethyl)glycine. Gaining insight into metal-ion phosphonate interactions in aqueous Co(II)-organophosphonate systems

Cobalt involvement in chemical and metallobiological processes entails largely unknown reactivity pathways with a variety of ligands. Such ligands include phosphonate and carboxylate-containing metal ion binders. In an attempt to investigate the nature and properties of species arising from aqueous interactions between Co(II) and N,N-bis(phosphonomethyl)-glycine (H₅NTA2P), reactions between the two led to an assembly of species in (NH₄)₄[Co(H₂O)₆][(H₂O)₂Co(HNTA2P)Co(NH₃)₂(H₂O)₃]₂[Co(NTA2P)(H₂O)₂]₂ · 10H₂O · 1.36CH₃CH₂OH (1) at pH ∼ 5.5. The analytical, spectroscopic and X-ray data on 1 reveal mononuclear and dinuclear complexes of Co(II) surrounded by oxygens, belonging to terminal carboxylates, phosphonates and bound water molecules, and nitrogen atoms from coordinated ammonia and H_xNTA2P^q− (x = 1, q = 4; x = 0, q = 5) ligands. Worth noting is the variable protonation state of the bound diphosphonate ligand and its ability to bridge two Co(II) centers with ostensibly differing coordination spheres. The assembly of three Co(II) species of variable nuclearity and composition attests to the importance of pH-specific conditions, under which “capturing” of more than one species can be achieved for a given Co(II):H₅NTA2P stoichiometry in the presence of ammonia. Collectively, 1 provides a rare glimpse of a “slice” of the aqueous speciation of the binary Co(II)-H₅NTA2P system, while its lattice composition projects key structural features in Co(II)-carboxyphosphonate materials.