Can we explain the allergenicity of peanuts on the basis of the three-dimensional structure of its allergens and use the information to devise means of eliminating peanut allergy?

Helical bundles are found in all the known structures of peanut allergens. The peptide fragments, which survive gastrointestinal digestion of the allergens and are absorbed intact, are hypothesized to reassociate and form stable helical bundles in the circulation, which could elicit a specific IgE response resulting in peanut allergy. The hypothesis is supported by the finding of a diminished allergenicity of an isoform of the peanut allergen, Ara h 3, which has a major deletion. A very probable consequence of this deletion is the reduced tendency to form a stable helix bundle. The discovery of structurally disrupted isoforms of the other peanut allergens and the breeding of plants that contain only those isoforms could lead to the elimination of peanut allergy.     

Contrasting associations of polymorphisms in FcγRIIa and DC-SIGN with the clinical presentation of dengue infection in a Mexican population

Dengue virus (DENV) causes a spectrum of illness from asymptomatic infection, to a mild febrile illness, to occasional more severe complications including hemorrhage and shock. Dengue is endemic in the state of Morelos, Mexico. Two single nucleotide polymorphisms (SNPs), rs1801274 of FcγRIIa and rs4804803 of DC-SIGN, have been associated with protection from or susceptibility to severe dengue infection. Both of these polymorphisms are located in genes for receptors with important roles in dengue pathogenesis, and their relationship with the clinical presentation of dengue infection in Mexican populations is unknown. In this study, real-time PCR was used to characterize the distribution of rs1801274 and rs4804803 in subjects with asymptomatic dengue infection (n = 145), uncomplicated dengue (n = 67), and severe dengue (n = 36) in Morelos. In contrast with previous studies, the histidine (A) variant of rs1801274 was associated with more mild infection: carrying the histidine allele (either homozygous or heterozygous) was associated with protection from symptomatic infection compared with asymptomatic (OR 0.51, p = 0.038). Histidine homozygotes were also less likely to present severe dengue (OR 0.34, p = 0.05). Logistic regression models confirm this association (OR 0.48, p = 0.04) and also indicate that the G allele of rs4804803 is associated with symptomatic dengue (OR 2.3, p = 0.08), after accounting for other biological factors including history of infection. This variant was rare in this study population, with a frequency of 5.4%. These findings reflect the complexity of influences on the development of severe dengue infection. The inclusion of asymptomatic infections and adjusted case definitions likely do not explain the entire disparity with previous findings. Interactions with other polymorphisms may explain why the association of rs1801274 is reversed in this population compared to others. This study demonstrates the importance of genetic association studies in multiple genetically distinct populations.     

Eleven microsatellite markers for the eastern gray squirrel (Sciurus carolinensis) and their utility in eastern fox squirrels (Sciurus niger) and red squirrels (Tamiasciurus hudsonicus)

The eastern gray squirrel (Sciurus carolinensis) often serves as a model organism for investigations of wildlife ecology. The authors developed 11 polymorphic microsatellite markers to facilitate future research questions. The number of alleles per locus ranged from three to ten and observed heterozygosities ranged from 0.143 to 0.786. Interspecific screening revealed that several loci were polymorphic in Sciurus niger (eight loci) and Tamiasciurus hudsonicus (four loci). These markers will aid in investigations of movements, social structure and mating tactics of eastern gray squirrel populations.     

An area-based study on intrapartum antibiotic prophylaxis for preventing group B streptococcus early-onset disease: advances and limitations

Introduction: The prevalence of maternal group-B-streptococcus (GBS) colonization and risk factors (RFs) for neonatal early-onset disease (EOD) in Europe are poorly defined. Large-scale information concerning adherence to recommendations for preventing GBS-EOD are lacking.

Materials and methods: This was a 3-month retrospective area-based study including all regional deliveries ≥35 weeks' gestation (in 2012). The sensitivity, specificity, positive and negative predictive values, odds ratio and receiver operating characteristic (ROC) curve for intrapartum antibiotic prophylaxis (IAP) among full-term and preterm deliveries and prolonged membrane rupture (PROM) were calculated.

Results: Among 7133 women, 259 (3.6%) were preterm (35–36 weeks' gestation). Full-term women were 6874, and 876 (12.7%) had at least 1?RF. Most women (6495) had prenatal screening and 21.4% (1390) were GBS positive.

IAP was given to 2369 (33.2%) women (preterm, n?=?166; full term, n?=?2203). Compared to full-term, preterm women were less likely to receive IAP when indicated (73.2% versus 90.3%, p?Conclusions: Large-scale prenatal screening and IAP are feasible. Women delivering preterm are less likely to receive IAP when indicated. Most unnecessary antibiotics are given in cases of PROM.     

Timecourse of mirror and counter-mirror effects measured with transcranial magnetic stimulation

The human mirror system has been the subject of much research over the past two decades, but little is known about the timecourse of mirror responses. In addition, it is unclear whether mirror and counter-mirror effects follow the same timecourse. We used single-pulse transcranial magnetic stimulation to investigate the timecourse of mirror and counter-mirror responses in the human brain. Experiment 1 demonstrated that mirror responses can be measured from around 200 ms after observed action onset. Experiment 2 demonstrated significant effects of counter-mirror sensorimotor training at all timepoints at which a mirror response was found in Experiment 1 (i.e. from 200 ms onward), indicating that mirror and counter-mirror responses follow the same timecourse. By suggesting similarly direct routes for mirror and counter-mirror responses, these results support the associative account of mirror neuron origins whereby mirror responses arise as a result of correlated sensorimotor experience during development. More generally, they contribute to theorizing regarding mirror neuron function by providing some constraints on how quickly mirror responses can influence social cognition.