Is hospital based MMR vaccination for children with egg allergy here to stay?

Egg allergy is incorrectly considered to constitute a contraindication to MMR in the community, despite a long history of its safe administration to egg allergic children. The product insert perpetuates this misinformation but the Irish guidelines from the RCPI are unequivocal. We reviewed all paediatric cases vaccinated in our hospital in 2007-2008. Forty seven of 91 children receiving vaccinations in hospital, had been referred for MMR due to concerns regarding egg allergy. In 32% (n=15), GP referral for vaccination was made despite correspondence from the clinic advising routine vaccination in the community. Nineteen were second MMR immunisations, which should all have occurred in the community. Unnecessary hospital referral for MMR vaccination is an extra burden on hospital resources, and causes unwarranted anxiety amongst parents of children with egg allergy. A change in practice seems difficult to achieve, as many referrals happen despite individualised correspondence to GPs and other referring clinicians outlining the current guidelines

Replication fork collisions cause pathological chromosomal amplification in cells lacking RecG DNA translocase

Duplication and transmission of chromosomes require precise control of chromosome replication and segregation. Here we present evidence that RecG is a major factor influencing these processes in bacteria. We show that the extensive DnaA-independent stable DNA replication observed without RecG can lead to replication of any area of the chromosome. This replication is further elevated following irradiation with UV light and appears to be perpetuated by secondary events that continue long after the elimination of UV lesions. The resulting pathological cascade is associated with an increased number of replication forks traversing the chromosome, sometimes with extensive regional amplification of the chromosome, and with the accumulation of highly branched DNA intermediates containing few Holliday junctions. We propose that the cascade is triggered by replication fork collisions that generate 3′ single-strand DNA flaps, providing sites for PriA to initiate re-replication of the DNA and thus to generate linear duplexes that provoke recombination, allowing priming of even further replication. Our results shed light on why termination of replication in bacteria is normally limited to a single encounter of two forks and carefully orchestrated within a restricted area, and explain how a system of multiple forks and random termination can operate in eukaryotes

Long-Range Chromosome Organization in E. coli: A Site-Specific System Isolates the Ter Macrodomain

The organization of the Escherichia coli chromosome into a ring composed of four macrodomains and two less-structured regions influences the segregation of sister chromatids and the mobility of chromosomal DNA. The structuring of the terminus region (Ter) into a macrodomain relies on the interaction of the protein MatP with a 13-bp target called matS repeated 23 times in the 800-kb-long domain. Here, by using a new method that allows the transposition of any chromosomal segment at a defined position on the genetic map, we reveal a site-specific system that restricts to the Ter region a constraining process that reduces DNA mobility and delays loci segregation. Remarkably, the constraining process is regulated during the cell cycle and occurs only when the Ter MD is associated with the division machinery at mid-cell. The change of DNA properties does not rely on the presence of a trans-acting mechanism but rather involves a cis-effect acting at a long distance from the Ter region. Two specific 12-bp sequences located in the flanking Left and Right macrodomains and a newly identified protein designated YfbV conserved with MatP through evolution are required to impede the spreading of the constraining process to the rest of the chromosome. Our results unravel a site-specific system required to restrict to the Ter region the consequences of anchoring the Ter MD to the division machinery

The unstructured C-terminus of the τ subunit of Escherichia coli DNA polymerase III holoenzyme is the site of interaction with the α subunit

The τ subunit of Escherichia coli DNA polymerase III holoenzyme interacts with the α subunit through its C-terminal Domain V, τC16. We show that the extreme C-terminal region of τC16 constitutes the site of interaction with α. The τC16 domain, but not a derivative of it with a C-terminal deletion of seven residues (τC16Δ7), forms an isolable complex with α. Surface plasmon resonance measurements were used to determine the dissociation constant (KD) of the α−τC16 complex to be ∼260 pM. Competition with immobilized τC16 by τC16 derivatives for binding to α gave values of KD of 7 μM for the α−τC16Δ7 complex. Low-level expression of the genes encoding τC16 and τC16▵7, but not τC16Δ11, is lethal to E. coli. Suppression of this lethal phenotype enabled selection of mutations in the 3′ end of the τC16 gene, that led to defects in α binding. The data suggest that the unstructured C-terminus of τ becomes folded into a helix–loop–helix in its complex with α. An N-terminally extended construct, τC24, was found to bind DNA in a salt-sensitive manner while no binding was observed for τC16, suggesting that the processivity switch of the replisome functionally involves Domain IV of τ

Dynamics of Genome Rearrangement in Bacterial Populations

Genome structure variation has profound impacts on phenotype in organisms ranging from microbes to humans, yet little is known about how natural selection acts on genome arrangement. Pathogenic bacteria such as Yersinia pestis, which causes bubonic and pneumonic plague, often exhibit a high degree of genomic rearrangement. The recent availability of several Yersinia genomes offers an unprecedented opportunity to study the evolution of genome structure and arrangement. We introduce a set of statistical methods to study patterns of rearrangement in circular chromosomes and apply them to the Yersinia. We constructed a multiple alignment of eight Yersinia genomes using Mauve software to identify 78 conserved segments that are internally free from genome rearrangement. Based on the alignment, we applied Bayesian statistical methods to infer the phylogenetic inversion history of Yersinia. The sampling of genome arrangement reconstructions contains seven parsimonious tree topologies, each having different histories of 79 inversions. Topologies with a greater number of inversions also exist, but were sampled less frequently. The inversion phylogenies agree with results suggested by SNP patterns. We then analyzed reconstructed inversion histories to identify patterns of rearrangement. We confirm an over-representation of “symmetric inversions”—inversions with endpoints that are equally distant from the origin of chromosomal replication. Ancestral genome arrangements demonstrate moderate preference for replichore balance in Yersinia. We found that all inversions are shorter than expected under a neutral model, whereas inversions acting within a single replichore are much shorter than expected. We also found evidence for a canonical configuration of the origin and terminus of replication. Finally, breakpoint reuse analysis reveals that inversions with endpoints proximal to the origin of DNA replication are nearly three times more frequent. Our findings represent the first characterization of genome arrangement evolution in a bacterial population evolving outside laboratory conditions. Insight into the process of genomic rearrangement may further the understanding of pathogen population dynamics and selection on the architecture of circular bacterial chromosomes

Theoretical investigation of the effect of subtle structural dynamics on CO2 sorption in TIFSIX-3-Ni, a hybrid ultramicroporous material (HUM)

The release of carbon dioxide (CO2) emissions into the atmosphere is a leading contributor to global warming. Carbon capture and sequestration (CCS) strives to mitigate the effects of CO2 on the atmosphere, traditionally by expensive and energy-intensive chemisorptive approaches. CO2 capture by physisorbents such as hybrid ultramicroporous materials (HUMs) is a step toward cheaper and more efficient CCS. In this study, the effect of pyrazine ring orientation upon CO2 adsorption is investigated for TIFSIX-3-Ni, a leading HUM for CO2 selectivity. Rigid systems are constructed by eliminating disorder from the unit cell as determined by in situ characterization. Density Functional Theory (DFT) and Grand Canonical Monte Carlo (GCMC) methods are used to investigate the effect of tilting and ordering pyrazine rings upon CO2 loading and isosteric heat of adsorption (Qst). Results show that more edge to face interactions between pyrazine CH moieties and the CO2 molecule induce a preferred binding site. Systems with chemically distinct binding sites exhibit a Qst trend comparable to that which is experimentally observed, showing first preference for binding in smaller pores using models treated with both UFF and OPLS-AA Lennard-Jones parameters. It is also noted that the degree of pyrazine ring tilting affects the energetics of the sorbent-sorbate interactions, meriting further study. This work highlights the importance of subtle structural dynamics in adsorption performance of leading porous materials, and can be used to guide further fine-tuning of physisorbent materials for gas sorption applications

The process of spiritually-inspired lifework

Bibliography: p. 131-13

Double-stranded oligonucleotides and uses therefor

The present invention relates generally to the field of screening or diagnostic applications in which a target is required to be displayed for binding to another molecule, or interaction or reaction with another molecule. In particular, the present invention relates to the use of DNA/protein interactions to immobilize or present one or more biomolecules for screening purposes. The present invention more particularly relates to double-stranded oligonucleotides, wherein said oligonucleotide comprises a first strand and a second strand, wherein: (a) said first strand comprises the sequence: 5'-NC R ND G T T G T A A C N0 A-3' (SEQ ID NO: 1) or an analogue or derivative of said sequence; and (b) said second strand comprises the sequence: 5'-T ND G T T A C A A C ND T NC -3' (SEQ ID NO: 2) or an analogue or derivative of said sequence wherein R is a purine, NC and ND are each a DNA or RNA residue or analogue thereof, ND residues in said first strand and said second strand are sufficiently complementary to permit said ND residues to be annealed in the double-stranded oligonucleotide, and the sequence 5'-GTTGTAAC-3' (SEQ ID NO: 3) of said first strand is annealed to the complementary sequence 5' GTTACAAC-3' (SEQ ID NO: 4) of said second strand