Ion-Ion and Ion-Molecule Reactions at the Surface of Proteins Produced by Nanospray. Information on the Number of Acidic Residues and Control of the Number of Ionized Acidic and Basic Residues

Mass Spectra of charge states of folded proteins were obtained with nanospray and aqueous solution containing 20 μM the protein (ubiquitin, cytochrome c, lysozyme) and one of the NaA salts NaCl, NaI, NaAc (acetate) (1–10 mM). At very low collision activated decomposition (CAD), the mass spectra of a protein with charge z exhibited a replacement of zH+ with zNa+ and also multiple adducts of NaA. Higher CAD converts the NaA adduct peaks to Na minus H peaks. These must be due to loss of HA where the H was provided by the protein. The degree of HA loss with increasing CAD followed the order I < Cl < Ac. Significantly, the intensity of the ions with n (Na minus H) adducts showed a downward break past an nMAX which is equal to the number of acidic residues of the protein plus the charge of the protein. All the observations could be rationalized within the framework of the electrospray mechanism and the charge residue model, which predict that due to extensive evaporation of solvent, the solutes will reach very high concentrations in the final charged droplets. At such high concentrations, positive ions such as Na+, NH4+ form ion pairs with ionized acidic residues and the negative A− form ion pairs with ionized basic residues of the protein. Adducts of Na+, and NaA to backbone amide groups occur also. This reaction mechanism fits all the experimental observations and provides predictions that the number of acidic and basic groups at the surface of the gaseous protein that remain ionized can be controlled by the absence or presence of additives to the solution

Prevalence and independent risk factors for hearing loss in NICU infants

Aim: To determine the prevalence and independent relationship between hearing loss and risk factors in a representative neonatal intensive care unit (NICU) population. Methods: Automated auditory brainstem response (AABR) hearing screening has been introduced since 1998 in the Dutch NICUs. After a second AABR failure, diagnostic ABR was used to establish diagnosis of hearing loss. Newborns who died before the age of 3 months were excluded. In the present study only the NICU infants who were born with a gestational age &lt;30 weeks and/or a birth weight &lt;1000 g between October 1, 1998 and January 1, 2002 were included. Risk factors included in the study were familial hearing loss, in utero infections, craniofacial anomalies, birth weight &lt;1500g, hyperbilirubinemia, ototoxic medications, cerebral complications, severe birth asphyxia, assisted ventilation ≥5 days and syndromes. Results: A nationwide cohort of 2186 newborns were included. Mean gestational age was 28.5 weeks (SD 1.6) and mean birth weight was 1039 g (SD 256). Prevalence of uni- or bilateral hearing loss was 3.2% (71/2186; 95% CI 2.6-4.1). Multivariate analysis revealed that the only independent risk factors for hearing loss were severe birth asphyxia (OR 1.7; 95% CI 1.0-2.7) and assisted ventilation ≥5 days (OR 3.6; 95% CI 2.1-6.0). Conclusion: The prevalence of hearing loss in a representative NICU population was 3.2%. Independent risk factors for hearing loss were severe birth asphyxia and assisted ventilation ≥5 days.</p

Hearing loss by week of gestation and birth weight in very preterm neonates

OBJECTIVE: To gain insight into health and related costs associated with very preterm births, one needs accurate information about the prevalence of the disabling conditions, including neonatal hearing loss (NHL).STUDY DESIGN: We assessed the prevalence of NHL by week of gestation and categories of birth weight in very preterm neonates. Results of the 2-stage Automated Auditory Brainstem Response nationwide Newborn Hearing Screening Program in Dutch Neonatal Intensive Care Units and diagnostic examinations were centrally registered between October 1998 and December 2012 and included in this study. NHL was defined as impaired when the neonate conventional Auditory Brainstem Response level exceeded 35 dB near Hearing Level at diagnostic examination. Birth weight was stratified into &lt;750 g, 750-999 g, 1000-1249 g, 1250-1499 g, and ≥ 1500 g, and by small for gestational age (SGA; &lt;10th percentile) vs appropriate for gestational age. Logistic regression analyses and recursive partitioning were performed.RESULTS: In total, 18,564 very preterm neonates were eligible. The prevalence of NHL consistently increased with decreasing week of gestation (1.2%-7.5% from 31 to 24 weeks) and decreasing birth weight (1.4%-4.8% from ≥ 1500 g to &lt;750 g, all P &lt; .002). Most vulnerable to NHL were girls &lt;28 weeks, boys &lt;30 weeks, and SGA neonates. The SGA effect started at 27 weeks.CONCLUSIONS: Gestational age and birth weight quantify the risk of NHL. This information can be used at the individual level for parent counseling and at the population level for medical decision making.</p

Evaluation of Treatment Thresholds for Unconjugated Hyperbilirubinemia in Preterm Infants:Effects on Serum Bilirubin and on Hearing Loss?

Background: Severe unconjugated hyperbilirubinemia may cause deafness. In the Netherlands, 25% lower total serum bilirubin (TSB) treatment thresholds were recently implemented for preterm infants.Objective: To determine the rate of hearing loss in jaundiced preterms treated at high or at low TSB thresholds.Design/Methods: In this retrospective study conducted at two neonatal intensive care units in the Netherlands, we included preterms (gestational age 35 dB).Results: There were 479 patients in the high and 144 in the low threshold group. Both groups had similar gestational ages (29.5 weeks) and birth weights (1300 g). Mean and mean peak TSB levels were significantly lower after the implementation of the novel thresholds: 152 +/- 43 mu mol/L and 212 +/- 52 mu mol/L versus 131 +/- 37 mu mol/L and 188 +/- 46 mu mol/L for the high versus low thresholds, respectively (PConclusions: Implementation of lower treatment thresholds resulted in reduced mean and peak TSB levels. The incidence of hearing impairment in preterms with a gestational age</p

Referral patterns of children with poor growth in primary health care

Background. To promote early diagnosis and treatment of short stature, consensus meetings were held in the mid nineteen nineties in the Netherlands and the UK. This resulted in guidelines for referral. In this study we evaluate the referral pattern of short stature in primary health care using these guidelines, comparing it with cut-off values mentioned by the WHO. Methods. Three sets of referral rules were tested on the

Screening rules for growth to detect celiac disease: A case-control simulation study

Background: It is generally assumed that most patients with celiac disease (CD) have a slowed growth in terms of length (or height) and weight. However, the effectiveness of slowed growth as a tool for identifying children with CD is unknown. Our aim is to study the diagnostic efficiency of several growth criteria used to detect CD children. Methods: A case-control simulation study was carried out. Longitudinal length and weight measurements from birth to 2.5 years of age were used from three groups of CD patients (n = 134) (one group diagnosed by screening, two groups with clinical manifestations), and a reference group obtained from the Social Medical Survey of Children Attending Child Health Clinics (SMOCC) cohort (n = 2,151) in The Netherlands. The main outcome measures were sensitivity, specificity and positive predictive value (PPV) for each criterion. Results: Body mass index (BMI) performed best for the groups with clinical manifestations. Thirty percent of the CD children with clinical manifestations and two percent of the reference children had a BMI Standard Deviation Score (SDS) less than -1.5 and a decrease in BMI SDS of at least -2.5 (PPV = 0.85%). The growth criteria did not discriminate between the screened CD group and the reference group. Conclusion: For the CD children with clinical manifestations, the most sensitive growth parameter is a decrease in BMI SDS. BMI is a better predictor than weight, and much better than length or height. Toddlers with CD detected by screening grow normally at this stage of the disease

Neural progenitor cells from an adult patient with fragile X syndrome

BACKGROUND: Currently, there is no adequate animal model to study the detailed molecular biochemistry of fragile X syndrome, the leading heritable form of mental impairment. In this study, we sought to establish the use of immature neural cells derived from adult tissues as a novel model of fragile X syndrome that could be used to more fully understand the pathology of this neurogenetic disease. METHODS: By modifying published methods for the harvest of neural progenitor cells from the post-mortem human brain, neural cells were successfully harvested and grown from post-mortem brain tissue of a 25-year-old adult male with fragile X syndrome, and from brain tissue of a patient with no neurological disease. RESULTS: The cultured fragile X cells displayed many of the characteristics of neural progenitor cells, including nestin and CD133 expression, as well as the biochemical hallmarks of fragile X syndrome, including CGG repeat expansion and a lack of FMRP expression. CONCLUSION: The successful production of neural cells from an individual with fragile X syndrome opens a new avenue for the scientific study of the molecular basis of this disorder, as well as an approach for studying the efficacy of new therapeutic agents

Genome-wide identification of directed gene networks using large-scale population genomics data

Identification of causal drivers behind regulatory gene networks is crucial in understanding gene function. Here, we develop a method for the large-scale inference of gene–gene interactions in observational population genomics data that are both directed (using local genetic instruments as causal anchors, akin to Mendelian Randomization) and specific (by controlling for linkage disequilibrium and pleiotropy). Analysis of genotype and whole-blood RNA-sequencing data from 3072 individuals identified 49 genes as drivers of downstream transcriptional changes (Wald P < 7 × 10−10), among which transcription factors were overrepresented (Fisher’s P = 3.3 × 10−7). Our analysis suggests new gene functions and targets, including for SENP7 (zinc-finger genes involved in retroviral repression) and BCL2A1 (target genes possibly involved in auditory dysfunction). Our work highlights the utility of population genomics data in deriving directed gene expression networks. A resource of trans-effects for all 6600 genes with a genetic instrument can be explored individually using a web-based browser

Genome-wide association analyses identify new Brugada syndrome risk loci and highlight a new mechanism of sodium channel regulation in disease susceptibility.

Brugada syndrome (BrS) is a cardiac arrhythmia disorder associated with sudden death in young adults. With the exception of SCN5A, encoding the cardiac sodium channel Na1.5, susceptibility genes remain largely unknown. Here we performed a genome-wide association meta-analysis comprising 2,820 unrelated cases with BrS and 10,001 controls, and identified 21 association signals at 12 loci (10 new). Single nucleotide polymorphism (SNP)-heritability estimates indicate a strong polygenic influence. Polygenic risk score analyses based on the 21 susceptibility variants demonstrate varying cumulative contribution of common risk alleles among different patient subgroups, as well as genetic associations with cardiac electrical traits and disorders in the general population. The predominance of cardiac transcription factor loci indicates that transcriptional regulation is a key feature of BrS pathogenesis. Furthermore, functional studies conducted on MAPRE2, encoding the microtubule plus-end binding protein EB2, point to microtubule-related trafficking effects on Na1.5 expression as a new underlying molecular mechanism. Taken together, these findings broaden our understanding of the genetic architecture of BrS and provide new insights into its molecular underpinnings