School Well-Being and Academic Performance of Children With Juvenile Idiopathic Arthritis: A National Register-Based Study.

OBJECTIVE: We aimed to investigate how school well-being (SWB) and academic performance of children with juvenile idiopathic arthritis (JIA) compare to their peers on a national level using the Danish national registers. Further, we investigated the potential influence of socioeconomic status (SES). METHODS: A population-wide, register-based, cross-sectional study was performed. We compared the results of children with and without JIA in the Danish National Well-Being Questionnaire (DNWQ), the National Danish School Testing (NDST), and their ninth grade (aged approximately 16 yrs) final school marks in Danish and mathematics. The results were analyzed using adjusted ordinal logistic regression (SWB) and linear regression (tests and marks). RESULTS: In separate cohorts, we included a total of 505,340 children answering the DNWQ, 812,461 children with NDST results, and the ninth-grade final marks of 581,804 children. Of these children, 1042, 1541, and 1410, respectively, fulfilled the criteria of JIA. Children with JIA reported SWB comparable to their peers, except for the question "Do you perform well in school?" (odds ratio 0.89, 95% CI 0.81-0.99). In the NDST, the children with JIA in general did just as well as their peers. We found no differences in the ninth-grade final marks in either Danish or mathematics. Stratifying the analyses on SES showed no significant differences in the associations. CONCLUSION: Overall, children with JIA report SWB comparable to that of children without JIA and perform equally well in school as children without JIA.

Free-energy decomposition of salt effects on the solubilities of small molecules and the role of excluded-volume effects.

The roles of cations and anions are different in the perturbation on solvation, and thus, the analyses of the separated contributions from cations and anions are useful to establish molecular pictures of ion-specific effects. In this work, we investigate the effects of cations, anions, and water separately in the solvation of n-alcohols and n-alkanes by free-energy decomposition. By utilising energy-representation theory of solvation, we address the contributions arising from the direct solute-solvent interactions and the excluded-volume effects. It is found that the change in solvation of n-alcohols and n-alkanes upon addition of salt depends primarily on the anion species. The direct interaction between the anion and solute is in agreement with the Setschenow coefficient in terms of the ranking of salting-in and salting-out for n-alkanes, which corresponds to the extent of accumulation of the anion on the solute surface. For each of the n-alcohols and n-alkanes examined, the excluded-volume component in the Setschenow coefficient is well correlated to the (total) Setschenow coefficient when the salt effects are concerned. The ranking of the excluded-volume component in the variation of the salt species is parallel to the water contribution, which is correlated further to the change in the water density upon the addition of the salt.

Increase in peg-asparaginase clearance as a predictor for inactivation in patients with acute lymphoblastic leukemia.

Asparaginase is an essential component of acute lymphoblastic leukemia (ALL) therapy, yet its associated toxicities often lead to treatment discontinuation, increasing the risk of relapse. Hypersensitivity reactions include clinical allergies, silent inactivation, or allergy-like responses. We hypothesized that even moderate increases in asparaginase clearance are related to later inactivation. We therefore explored mandatory monitoring of asparaginase enzyme activity (AEA) in patients with ALL aged 1-45 years treated according to the ALLTogether pilot protocol in the Nordic and Baltic countries to relate mean AEA to inactivation, to build a pharmacokinetic model to better characterize the pharmacokinetics of peg-asparaginase and assess whether an increased clearance relates to subsequent inactivation. The study analyzed 1631 real-time AEA samples from 253 patients, identifying inactivation in 18.2% of the patients. This inactivation presented as mild allergy (28.3%), severe allergy (50.0%), or silent inactivation (21.7%). A pharmacokinetic transit compartment model was used to describe AEA-time profiles, revealing that 93% of patients with inactivation exhibited prior increased clearance, whereas 86% of patients without hypersensitivity maintained stable clearance throughout asparaginase treatment. These findings enable prediction of inactivation and options for either dose increments or a shift to alternative asparaginase formulations to optimize ALL treatment strategies.

Psychiatric Morbidity Is Common Among Children With Juvenile Idiopathic Arthritis: A National Matched Cohort Study.

OBJECTIVE: Juvenile idiopathic arthritis (JIA) is a chronic rheumatic disease that causes joint inflammation and pain. Previous studies have indicated affected mental health and increased risk of psychiatric conditions among patients with JIA. We aimed to explore differences in psychiatric morbidity between children with JIA and their peers. We further studied if parental socioeconomic status (SES) influences the association between JIA and the risk of psychiatric morbidity. METHODS: We used a matched cohort design to estimate the association between JIA and psychiatric disease. Children with JIA, born between 1995 and 2014, were identified in Danish national registers. Based on birth registers, we randomly selected 100 age- and sex-matched children per index child. Index date was the date of the fifth JIA diagnosis code or the date of matching for reference children. End of follow-up was the date of psychiatric diagnosis, death, emigration, or December 31, 2018, whatever came first. Data were analyzed using a Cox proportional hazard model. RESULTS: We identified 2086 children with JIA with a mean age at diagnosis of 8.1 years. Children with JIA had a 17% higher instantaneous risk of a psychiatric diagnosis when compared with the reference group, with an adjusted hazard ratio of 1.17 (95% CI 1.02-1.34). Relevant associations were found only for depression and adjustment disorders. Stratifying our analysis for SES showed no modifying effect of SES. CONCLUSION: Children with JIA had a higher risk of psychiatric diagnoses compared to their peers, especially diagnoses of depression and adjustment disorders. The association between JIA and psychiatric disease did not depend on parental SES.

Salt Effects on Caffeine across Concentration Regimes.

Salts affect the solvation thermodynamics of molecules of all sizes; the Hofmeister series is a prime example in which different ions lead to salting-in or salting-out of aqueous proteins. Early work of Tanford led to the discovery that the solvation of molecular surface motifs is proportional to the solvent accessible surface area (SASA), and later studies have shown that the proportionality constant varies with the salt concentration and type. Using multiscale computer simulations combined with vapor-pressure osmometry on caffeine-salt solutions, we reveal that this SASA description captures a rich set of molecular driving forces in tertiary solutions at changing solute and osmolyte concentrations. Central to the theoretical work is a new potential energy function that depends on the instantaneous surface area, salt type, and concentration. Used in, e.g., Monte Carlo simulations, this allows for a highly efficient exploration of many-body interactions and the resulting thermodynamics at elevated solute and salt concentrations.

Outdoor Alternaria and Cladosporium spores and acute asthma.

BACKGROUND: Outdoor Alternaria and Cladosporium spores are ubiquitous. Few studies have assessed their impact on asthma hospitalizations providing conflicting results, mainly focused on vulnerable paediatric populations. We aimed to study the impact of outdoor Alternaria and Cladosporium concentrations on acute hospitalizations in the Capital Region of Denmark. METHODS: This is a bi-directional case-crossover study with 26 years of national registry data at individual level on acute asthma hospitalizations and daily average data on Alternaria and Cladosporium, pollen (Artemisia, Poaceae), maximal temperature, and air pollution. Conditional logistic regression models were applied to assess the associations. Concentration quartiles at lag 0 were used for categorizing the exposure. RESULTS: For lags 0-2, the odds of hospitalization were significantly higher for both Alternaria and Cladosporium at concentration quartile 2-4 compared with quartile 1. When stratified for age and sex, odds of hospitalization at Alternaria quartiles 2-4 were significantly higher in males below 40 years at lag 0-2, and at lag 0 in females (18-30 years), while quartiles 2-4 of Cladosporium concentrations were associated with significantly higher odds in boys (0-17 years) at lag 1-3, males (18-39 years) at lag 0-1, females (18-39 years) at lag 1-2, males (40-64 years) at lag 0-2, females (40-64 years) at lag 0 and 2, in seniors (65+ years) male at lag 1-2 and female at lag 0-1. The effect of Alternaria varied significantly depending on the level of Cladosporium (p < .0001). CONCLUSION: Ambient Alternaria and Cladosporium spores can induce asthma hospitalizations. Males are more susceptible to both genera. Males and females under age 40 years are more susceptible to Alternaria.

Maternal Pre-Pregnancy BMI, Offspring Adiposity in Late Childhood, and Age of Weaning: A Causal Mediation Analysis.

Infant feeding practices have been hypothesized to influence offspring's body mass index (BMI) later in life, and women with overweight or obesity tend to wean their infants earlier than women with healthy BMI. We, therefore, aimed to investigate how much early age of weaning mediated the maternal-offspring adiposity relationship. The study included 4920 mother-child pairs from the Avon Longitudinal Study of Parents and Children birth cohort. G-computation was applied to estimate the natural direct (NDE) and indirect (NIE) effects, via the age of weaning (<3 months, 3 months, >3 months), of maternal pre-pregnancy overweight or obesity on offspring's BMI and fat mass index. The NDE of maternal overweight or obesity on offspring BMI at 17 years old was 2.63 kg/m2 (95% CI: 2.27 to 2.99). The NIE via the age of weaning was 0.02 kg/m2 (95% CI: 0.00 to 0.04), corresponding to 0.8% of the total effect. Similar results were observed for the offspring's fat mass index. The NDE and NIE were similar to the main analyses when we looked at the relationship stratified by breastfeeding status. Our study found a minimal influence of age of weaning on the pathway between maternal and offspring adiposity, indicating the age of weaning may not be a key mediator.

Childhood socioeconomic position and cardiometabolic risk in young adulthood- the impact of mental health.

BACKGROUND: Low socioeconomic position in childhood is associated with greater cardiometabolic disease risk later in life. The aim of the current study is to examine the mediating impact of mental health on the association between childhood socioeconomic position and cardiometabolic disease risk in young adulthood. METHODS: We used a combination of national registers, longitudinal questionnaire-data and clinical measurements from a sub-sample (N = 259) of a Danish youth cohort. Childhood socioeconomic position was indicated by the educational level of the mother and the father at age 14. Mental health was measured by four different symptom scales at four age-points (age 15, 18, 21 and 28), and combined into one global score. Cardiometabolic disease risk was measured by nine biomarkers at age 28-30 and combined into one global score by sample-specific z-scores. We conducted analyses within the causal inference framework and evaluated the associations using nested counterfactuals. RESULTS: We found an inverse association between childhood socioeconomic position and cardiometabolic disease risk in young adulthood. The proportion of the association which was mediated by mental health was 10 (95% CI: -4; 24) % and 12 (95% CI: -4; 28) % using educational level of the mother and the father as indicator, respectively. CONCLUSIONS: Accumulated poorer mental health in childhood, youth and early adulthood partially explained the association between low childhood socioeconomic position and increased cardiometabolic disease risk in young adulthood. The results of the causal inference analyses rely on the underlying assumptions and correct depiction of the DAG. Since these are not all testable, we cannot exclude violations that potentially could bias the estimates. If the findings can be replicated, this would support a causal relationship and direct potentials for intervention. However, the findings point to a potential for intervention in young age in order to impede the translation of childhood social stratification into later cardiometabolic disease risk disparities.

Chemometrics in Protein Formulation: Stability Governed by Repulsion and Protein Unfolding.

Therapeutic proteins can be challenging to develop due to their complexity and the requirement of an acceptable formulation to ensure patient safety and efficacy. To date, there is no universal formulation development strategy that can identify optimal formulation conditions for all types of proteins in a fast and reliable manner. In this work, high-throughput characterization, employing a toolbox of five techniques, was performed on 14 structurally different proteins formulated in 6 different buffer conditions and in the presence of 4 different excipients. Multivariate data analysis and chemometrics were used to analyze the data in an unbiased way. First, observed changes in stability were primarily determined by the individual protein. Second, pH and ionic strength are the two most important factors determining the physical stability of proteins, where there exists a significant statistical interaction between protein and pH/ionic strength. Additionally, we developed prediction methods by partial least-squares regression. Colloidal stability indicators are important for prediction of real-time stability, while conformational stability indicators are important for prediction of stability under accelerated stress conditions at 40 °C. In order to predict real-time storage stability, protein-protein repulsion and the initial monomer fraction are the most important properties to monitor.

The effect of air quality on sleep and cognitive performance in school children aged 10-12 years: a double-blinded, placebo-controlled, crossover trial.

OBJECTIVES: To investigate the effect of CO2 during sleep on next-morning cognitive performance in young schoolchildren, the authors performed a double-blind fully balanced crossover placebo-controlled study. MATERIAL AND METHODS: The authors included 36 children aged 10-12 years in the climate chamber. The children slept at 21°C in 6 groups each at 3 different conditions separated by 7 days in a random order. Conditions were as follows: high ventilation with CO2 at 700 ppm, high ventilation with added pure CO2 at 2000-3000 ppm, and reduced ventilation with CO2 at 2-3000 ppm and bioeffluents. Children were subjected to a digital cognitive test battery (CANTAB) in the evening prior to sleep and on the next morning after breakfast. Sleep quality was monitored with wrist actigraphs. RESULTS: There were no significant exposure effects on cognitive performance. Sleep efficiency was significantly lower at high ventilation with CO2 at 700 ppm which is considered to be a chance effect. No other effects were seen, and no relation between air quality during sleep and next-morning cognitive performance was observed in the children emitting an estimated 10 lCO2/h per child. CONCLUSIONS: No effect of CO2 during sleep was found on next day cognition. The children were awakened in the morning, and spent from 45-70 min in well-ventilated rooms before they were tested. Hence, it cannot be precluded that the children have benefitted from the good indoor air quality conditions before and during the testing period. The slightly better sleep efficiency during high CO2 concentrations might be a chance finding. Hence, replication is needed in actual bedrooms controlling for other external factors before any generalizations can be made. Int J Occup Med Environ Health. 2023;36(2):177-91.

Multiple health complaints in preadolescence and hospital contacts during adolescence: a prospective cohort study.

Multiple health complaints (MHC) is increasing among preadolescents in many countries, but their prognostic effect for individual thriving or societal resource use is scarcely studied. This makes interpreting the significance of this increase challenging. We contribute by examining whether MHC in preadolescence predicts hospital contacts in adolescence by doing a nation-wide population-based cohort-study following preadolescents from the Danish National Birth-Cohort from 2010 to 2018. 96,382 children were invited at age 11. Responses to a modified version of the Health Behaviour in School Children Symptom Checklist (headache, dizziness, stomachache, irritability, feeling nervous, difficulty in getting to sleep and feeling low) was dichotomized into MHC (≥ 2 concurrent symptoms, each with a frequency of at least weekly, yes/no). Hospital contacts were derived from Danish registers from the date of answering the questionnaire to December 31st 2018. Negative binomial regression estimated incidence rate ratios (IRRs) comparing children with MHC to children without. Analyses were further broken down by hospital sector (psychiatric/somatic) and contact type (in-patient/out-patient/emergency room). 47,365 (49.1%) responded. Mean age was 11.2 years, 52% girls. 10.3% of responders reported MHC. For hospital contacts, the unadjusted IRR was 1.74 [95% CI 1.65, 1.83]. Results were robust to adjustment for sociodemographic variables and somatic/psychiatric morbidity diagnosed before baseline, IRR 1.62 [95% CI 1.54-1.71]. In conclusion, MHC in preadolescents are prognostic of hospital contacts. This shows that we cannot ignore MHC, and to prevent potentially unhelpful healthcare use, we must act. Future research should focus on the underlying causes of MHC to understand which changes will be most helpful and thus how to act.

Temporal and regional differences in the incidence of hospital-diagnosed endometriosis: a Danish population-based study.

INTRODUCTION: Due to diagnostic challenges, normalization of symptoms and an overall lack of awareness among both patients and physicians, endometriosis is an underdiagnosed disease. This can result in delayed treatment and potentially worsening of the disease. Despite initiatives, such as patients' support organizations and specialized endometriosis referral centers, differences in awareness, socioeconomic factors and lifestyle, combined with varying distances to specialized referral centers, could result in regional differences in the degree of underdiagnosing. This study aims to explore temporal and regional variations in the incidence of endometriosis based on the Danish hospital discharge register, and shed light on the degree of underdiagnosing of endometriosis in Denmark. MATERIAL AND METHODS: This registry-based cohort study included all women aged 15-55 living in Denmark from 1990-2017. Participants were identified through the Danish Civil Registration system and endometriosis diagnoses received at a hospital were obtained from the Danish National Patient Registry. Incidence rates of diagnosed endometriosis were calculated for each year of the study period and for each municipality in Denmark. A Cox regression analysis, stratified by calendar time and adjusted for ethnic origin, household composition, highest educational level and family socioeconomic status, was performed to estimate the association between residence and likelihood of receiving a hospital-based diagnosis of endometriosis. RESULTS: The nationwide incidence rate of hospital-diagnosed endometriosis was 7.89 (95% confidence interval [CI] 7.80-7.99) per 10 000 person-years and the prevalence in 2017 was 1.63%. The results showed an overall increase in the incidence of diagnosed endometriosis of 46.8% (95% CI 32.9-62.2) during the study period and also displayed significant regional differences. After adjustments, women living in northern Jutland had the highest probability of receiving a hospital-based diagnosis of endometriosis (hazard ratio 1.13, 95% CI 1.09-1.18), whereas women living in northern Zealand had the lowest probability (hazard ratio 0.63, 95% CI 0.60-0.67) compared with eastern Jutland. These regional differences have become more evident over time. CONCLUSIONS: Our results reveal significant regional differences in the incidence of hospital-diagnosed endometriosis, suggesting that a significant number of women may be left behind without a diagnosis. Further studies are needed to assess the underlying reasons for the significant regional differences.

Counterintuitive Electrostatics upon Metal Ion Coordination to a Receptor with Two Homotopic Binding Sites.

The consecutive binding of two potassium ions to a bis(18-crown-6) analogue of Tröger's base (BCETB) in water was studied by isothermal titration calorimetry using four different salts, KCl, KI, KSCN, and K2SO4. A counterintuitive result was observed: the enthalpy change associated with the binding of the second ion is more negative than that of the first (ΔHbind,2° < ΔHbind,1°). This remarkable finding is supported by continuum electrostatic theory as well as by atomic scale replica exchange molecular dynamics simulations, where the latter robustly reproduces experimental trends for all simulated salts, KCl, KI, and KSCN, using multiple force fields. While an enthalpic K+-K+ attraction in water poses a small, but fundamentally important, contribution to the overall interaction, the probability of the collapsed conformation (COL) of BCETB, where both crown ether moieties (CEs) of BCETB are bent in toward the cavity, was found to increase successively upon binding of the first and second potassium ions. The promotion of the COL conformation reveals favorable intrinsic interactions between the potassium coordinated CEs, which further contribute to the observation that ΔHbind,2° < ΔHbind,1°. While the observed trend is independent of the counterion, the origin of the significantly larger magnitude of the difference ΔHbind,2° - ΔHbind,1° observed experimentally for KSCN was studied in light of the weaker hydration of the thiocyanate anion, resulting in an enrichment of thiocyanate ions close to BCETB compared to the other studied counterions.

Anion-cation contrast of small molecule solvation in salt solutions.

The contributions from anions and cations from salt are inseparable in their perturbation of molecular systems by experimental and computational methods, rendering it difficult to dissect the effects exerted by the anions and cations individually. Here we investigate the solvation of a small molecule, caffeine, and its perturbation by monovalent salts from various parts of the Hofmeister series. Using molecular dynamics and the energy-representation theory of solvation, we estimate the solvation free energy of caffeine and decompose it into the contributions from anions, cations, and water. We also decompose the contributions arising from the solute-solvent and solute-ions interactions and that from excluded volume, enabling us to pin-point the mechanism of salt. Anions and cations revealed high contrast in their perturbation of caffeine solvation, with the cations salting-in caffeine via binding to the polar ketone groups, while the anions were found to be salting-out via perturbations of water. In agreement with previous findings, the perturbation by salt is mostly anion dependent, with the magnitude of the excluded-volume effect found to be the governing mechanism. The free-energy decomposition as conducted in the present work can be useful to understand ion-specific effects and the associated Hofmeister series.

Pre-adolescents with multiple health complaints redeem more prescriptions: A follow-up study in the Danish National Birth Cohort.

Aims: This study aimed to examine the association between multiple health complaints (MHC) in pre-adolescence and prescription redemption in adolescence. Methods: This was a nationwide population-based study based on the Danish National Birth Cohort for an average of 6.9 years (2010-2018). A total of 96,382 children were invited at the age of 11. A modified version of the Health Behaviour in School Children Symptom Checklist was dichotomised into the World Health Organization's definition of MHC (⩾2 complaints, each with a frequency of at least weekly, yes/no). The number of prescriptions was retrieved from Danish registries. Negative binomial regression estimated incidence rate ratios (IRRs) comparing children with MHC to children without. Prescription redemption was further stratified by psychiatric/somatic medication and into subtypes of prescriptions. Results: A total of 47,365 (49.1%) children participated (Mage=11.2 years, 52% girls). MHC were reported by 10.3%. The unadjusted IRR (MHC vs. no MHC) of all types of redemptions was 1.57 (95% confidence interval (CI) 1.49-1.64). Results were robust to adjustment for socio-demographic variables and somatic/psychiatric morbidity at baseline (IRR=1.47; 95% CI 1.40-1.54). Associations were especially strong for psychiatric medication (adjusted IRR=3.88; 95% CI 3.43-4.40) and were modified by neither sex nor maternal education. Conclusions: MHC in pre-adolescents predict prescription redemption. This implies that changes in MHC might be indicative of changes in public health. This requires further study, as the cause of a change in reporting of symptoms might also cause a change in treatment response. The latter determines whether prescriptions are treating ill-being or needlessly medicalising subjective symptoms.

Asparaginase enzyme activity levels and toxicity in childhood acute lymphoblastic leukemia: a NOPHO ALL2008 study.

Asparaginase treatment is a mainstay in contemporary treatment of acute lymphoblastic leukemia (ALL), but substantial asparaginase-related toxicity may lead to jeopardized protocol compliance and compromises survival. We investigated the association between risk of asparaginase-associated toxicities (AspTox) and asparaginase enzyme activity (AEA) levels in 1155 children aged 1.0 to 17.9 years, diagnosed with ALL between July 2008 and March 2016, and treated according to the Nordic Society of Pediatric Hematology and Oncology (NOPHO) ALL2008 protocol. Patients with ≥2 blood samples for AEA measurement drawn 14 ± 2 days after asparaginase administration were included (6944 trough values). AEA was measurable (or >0 IU/L) in 955 patients, whereas 200 patients (17.3%) had asparaginase inactivation and few AspTox recorded. A time-dependent multiple Cox model of time to any first asparaginase-associated toxicity adjusted for sex and age was used. For patients with measurable AEA, we found a hazard ratio (HR) of 1.17 per 100 IU/L increase in median AEA (95% confidence interval [CI], 0.98-1.41; P = .09). For pancreatitis, thromboembolism, and osteonecrosis, the HRs were 1.40 (95% CI, 1.12-1.75; P = .002), 0.99 (95% CI, 0.70-1.40; P = .96), and 1.36 (95% CI, 1.04-1.77; P = .02) per 100 IU/L increase in median AEA, respectively. No significant decrease in the risk of leukemic relapse was found: HR 0.88 per 100 IU/L increase in AEA (95% CI, 0.66-1.16; P = .35). In conclusion, these results emphasize that overall AspTox and relapse are not associated with AEA levels, yet the risk of pancreatitis and osteonecrosis increases with increasing AEA levels.

Optimal interpregnancy interval in autism spectrum disorder: A multi-national study of a modifiable risk factor.

It is biologically plausible that risk of autism spectrum disorder (ASD) is elevated by both short and long interpregnancy intervals (IPI). We conducted a retrospective cohort study of singleton, non-nulliparous live births, 1998-2007 in Denmark, Finland, and Sweden (N = 925,523 births). Optimal IPI was defined as the IPI at which minimum risk was observed. Generalized additive models were used to estimate relative risks (RR) of ASD and 95% Confidence Intervals (CI). Population impact fractions (PIF) for ASD were estimated under scenarios for shifts in the IPI distribution. We observed that the association between ASD (N = 9302) and IPI was U-shaped for all countries. ASD risk was lowest (optimal IPI) at 35 months for all countries combined, and at 30, 33, and 39 months in Denmark, Finland, and Sweden, respectively. Fully adjusted RRs at IPIs of 6, 12, and 60 months were 1.41 (95% CI: 1.08, 1.85), 1.26 (95% CI: 1.02, 1.56), and 1.24 (95% CI: 0.98, 1.58) compared to an IPI of 35 months. Under the most conservative scenario PIFs ranged from 5% (95% CI: 1%-8%) in Denmark to 9% (95% CI: 6%-12%) in Sweden. The minimum ASD risk followed IPIs of 30-39 months across three countries. These results reflect both direct IPI effects and other, closely related social and biological pathways. If our results reflect biologically causal effects, increasing optimal IPIs and reducing their indications, such as unintended pregnancy and delayed age at first pregnancy has the potential to prevent a salient proportion of ASD cases. LAY SUMMARY: Waiting 35 months to conceive again after giving birth resulted in the least risk of autism. Shorter and longer intervals resulted in risks that were up to 50% and 85% higher, respectively. About 5% to 9% of autism cases might be avoided by optimizing birth spacing.

Coating of cochlear implant electrodes with bioactive DNA-loaded calcium phosphate nanoparticles for the local transfection of stimulatory proteins.

Calcium phosphate nanoparticles were loaded with nucleic acids to enhance the on-growth of tissue to a cochlear implant electrode. The nanoparticle deposition on a metallic electrode surface is possible by electrophoretic deposition (EPD) or layer-by-layer deposition (LbL). Impedance spectroscopy showed that the coating layer did not interrupt the electrical conductance at physiological frequencies and beyond (1-40,000 Hz). The transfection was demonstrated with the model cell lines HeLa and 3T3 as well as with primary explanted spiral ganglion neurons (rat) with the model protein enhanced green fluorescent protein (EGFP). The expression of the functional protein brain-derived neurotrophic factor (BDNF) was also shown. Thus, a coating of inner-ear cochlear implant electrodes with nanoparticles that carry nucleic acids will enhance the ongrowth of spiral ganglion cell axons for an improved transmission of electrical pulses.

Impact of Arginine-Phosphate Interactions on the Reentrant Condensation of Disordered Proteins.

Re-entrant condensation results in the formation of a condensed protein regime between two critical ion concentrations. The process is driven by neutralization and inversion of the protein charge by oppositely charged ions. Re-entrant condensation of cationic proteins by the polyvalent anions, pyrophosphate and tripolyphosphate, has previously been observed, but not for citrate, which has similar charge and size compared to the polyphosphates. Therefore, besides electrostatic interactions, other specific interactions between the polyphosphate ions and proteins must contribute. Here, we show that additional attractive interactions between arginine and tripolyphosphate determine the re-entrant condensation and decondensation boundaries of the cationic, intrinsically disordered saliva protein, histatin 5. Furthermore, we show by small-angle X-ray scattering (SAXS) that polyvalent anions cause compaction of histatin 5, as would be expected based solely on electrostatic interactions. Hence, we conclude that arginine-phosphate-specific interactions not only regulate solution properties but also influence the conformational ensemble of histatin 5, which is shown to vary with the number of arginine residues. Together, the results presented here provide further insight into an organizational mechanism that can be used to tune protein interactions in solution of both naturally occurring and synthetic proteins.

Charge Interactions in a Highly Charge-Depleted Protein.

Electrostatic forces are important for protein folding and are favored targets of protein engineering. However, interactions between charged residues are difficult to study because of the complex network of interactions found in most proteins. We have designed a purposely simple system to investigate this problem by systematically introducing individual and pairs of charged and titratable residues in a protein otherwise free of such residues. We used constant pH molecular dynamics simulations, NMR spectroscopy, and thermodynamic double mutant cycles to probe the structure and energetics of the interaction between the charged residues. We found that the partial burial of surface charges contributes to a shift in pKa value, causing an aspartate to titrate in the neutral pH range. Additionally, the interaction between pairs of residues was found to be highly context dependent, with some pairs having no apparent preferential interaction, while other pairs would engage in coupled titration forming a highly stabilized salt bridge. We find good agreement between experiments and simulations and use the simulations to rationalize our observations and to provide a detailed mechanistic understanding of the electrostatic interactions.