Non-monotonic variation with salt concentration of the second virial coefficient in protein solutions

The osmotic virial coefficient $B_2$ of globular protein solutions is calculated as a function of added salt concentration at fixed pH by computer simulations of the ``primitive model''. The salt and counter-ions as well as a discrete charge pattern on the protein surface are explicitly incorporated. For parameters roughly corresponding to lysozyme, we find that $B_2$ first decreases with added salt concentration up to a threshold concentration, then increases to a maximum, and then decreases again upon further raising the ionic strength. Our studies demonstrate that the existence of a discrete charge pattern on the protein surface profoundly influences the effective interactions and that non-linear Poisson Boltzmann and Derjaguin-Landau-Verwey-Overbeek (DLVO) theory fail for large ionic strength. The observed non-monotonicity of $B_2$ is compared to experiments. Implications for protein crystallization are discussed.Comment: 43 pages, including 17 figure

Integrating sequence and array data to create an improved 1000 Genomes Project haplotype reference panel

A major use of the 1000 Genomes Project (1000GP) data is genotype imputation in genome-wide association studies (GWAS). Here we develop a method to estimate haplotypes from low-coverage sequencing data that can take advantage of single-nucleotide polymorphism (SNP) microarray genotypes on the same samples. First the SNP array data are phased to build a backbone (or 'scaffold') of haplotypes across each chromosome. We then phase the sequence data 'onto' this haplotype scaffold. This approach can take advantage of relatedness between sequenced and non-sequenced samples to improve accuracy. We use this method to create a new 1000GP haplotype reference set for use by the human genetic community. Using a set of validation genotypes at SNP and bi-allelic indels we show that these haplotypes have lower genotype discordance and improved imputation performance into downstream GWAS samples, especially at low-frequency variants. © 2014 Macmillan Publishers Limited. All rights reserved

Child car restraints: Mandating type and seating row according to age with positive effect in regional city in Queensland, Australia

Road trauma is a leading cause of child injury worldwide. In highly motorised countries, injury as a passenger represents a major proportion of all child road deaths and hospitalisations. Australia is no exception, particularly since there are high levels of private motor vehicle travel to school in most Australian states. Recently the legislation governing the type of car restraints required for children aged under 7 years has changed in Australia, aligning requirements better with accepted best practice. However, it is unclear what effect these changes have had on children’s seating positions or the types of restraints used. A mixed methods evaluation of the impact of the new legislation on compliance was conducted at three times: baseline (Time 1); after announcement that changes were going to be implemented but before enforcement began (Time 2); and after enforcement commenced (Time 3). Measures of compliance were obtained using two methods: road-side observations of vehicles with child passengers; and parental self-report (intercept interviews conducted at Time 2 and Time 3 only). Results from the observations suggested an overall positive effect. Proportions of children occupying front seats decreased overall and use of dedicated child seats increased to almost 40% of the observed children by Time 3. However, almost a quarter of the children observed still occupied front seats. These results differed from those of the interview study where almost no children were reported as usually travelling in the front seat, and reported use of dedicated restraints with children was almost 90%, over twice that of the observations

Purification of β-1, 4-glucanase from ethylene-treated abscission zones of Sambucus nigra

Leaflet abscission in Sambucus nigra is the result of cell wall breakdown at the site of separation. Associated with wall degradation is an increase in the activity of the enzyme β1,4 glucanase (E.C.3.1.2.4) in the cells that comprise the abscission zone. The enzyme has been extracted from abscission zone tissue and purified using a substrate affinity column. A qualitative enzyme assay procedure has been developed and this has facilitated the purification process. The β1,4 glucanase enzyme has a pH optimum of 7 and a molecular mass of 54kDa. Antibodies have been raised to the purified protein. The role of the enzyme in the abscission process is discussed

Incidence and clinical significance of abdominal wall bruising in restrained children involved in motor vehicle crashes.

BACKGROUND: Children involved in motor vehicle crashes (MVC) can sustain bruising of the abdominal wall associated with seat belt restraint. The incidence of bruising and its relationship with significant intraabdominal injuries are not known. METHODS: An analysis of children involved in MVC between December 1998 and November 2002 was performed, using the crash surveillance database from the Partners for Child Passenger Safety (PCPS) project. Optimally (OR) or suboptimally (S-OR) restrained children aged 4 to 15 years were selected. The incidence of abdominal wall bruising was calculated then correlated with the type of restraint as well as any intraabdominal injury with an Abbreviated Injury Scale score > or =2. RESULTS: A total of 147,985 children in 102,548 crashes met study criteria. An abdominal bruise was noted in 1.33% of the children (n = 1,967; 881 OR and 1,086 S-OR). Significant intraabdominal injury was present in 309 children (0.21%, 95% CI 0.13 to 0.33), including 69 OR and 240 S-OR. The sensitivity, specificity, and positive and negative predictive values of abdominal wall bruising for a significant intraabdominal injury were 73.5%, 98.8%, 11.5%, and 99.9%, respectively. Children with a bruise were substantially more likely to have an intraabdominal injury than children without a bruise. (Odds Ratio 232.1, 95% CI, 75.9 to 710.3) Among those children with an abdominal bruise, 1% required an abdominal operation (n = 20). CONCLUSIONS: Abdominal wall bruising was relatively uncommon in both OR and S-OR children. Among restrained children involved in MVC, those with a bruise were 232 times more likely to have a significant intraabdominal injury when compared with those without a bruise. It is imperative to pursue intraabdominal injury in children with a bruise of the abdominal wall after MVC

Suboptimal restraint affects the pattern of abdominal injuries in children involved in motor vehicle crashes.

BACKGROUND: Both solid and hollow visceral abdominal injuries have been associated with the use of seat belts in children involved in motor vehicle crashes. The relationship between the types of restraint used and the pattern of abdominal injury is unknown. METHODS: A probability sample of restrained children involved in crashes was enrolled in an ongoing crash surveillance system (1998 through 2002) linking insurance claims data to telephone survey and crash investigation data. Significant abdominal injuries were considered when the Abbreviated Injury Scale (AIS) score was > or =2 and were defined as hollow visceral (HV; intestine, bladder), or solid visceral (liver, spleen, pancreas, kidney). Restraint type was categorized as optimal restraint (OR) or suboptimal restraint (S-OR) based on the child's age and size. RESULTS: For the 33 months of review, interviews were obtained for 13,558 restrained children aged 0 to 15 years, of which, 56% were OR (n = 7,591) and 44% were S-OR (n = 5,967). A significant abdominal injury was recorded in 78 children. A hollow visceral injury was recorded in 38 (9 OR and 29 S-OR), and a solid visceral injury in 32 (18 OR and 14 S-OR). Both hollow and solid visceral injuries were present in 8 children (2 OR and 6 S-OR). Suboptimally restrained children had a higher risk for hollow visceral injury when compared with optimally restrained children (Odds Ratio, 4.14 [95% Confidence Interval 1.33 to 13.22, P <.01]). CONCLUSIONS: Among restrained children with intraabdominal injuries, those who were suboptimally restrained were 4 times more likely to have a hollow visceral than a solid visceral injury when compared with those who were optimally restrained. This suggests that the mechanism of injury for hollow viscus may be directly related to the improper positioning of the restraint