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1.  Positive predictive value and completeness of prenatally assigned International Classification of Disease-10 kidney anomaly diagnoses in the Danish National Patient Registry 
Clinical Epidemiology  2016;8:9-14.
Restricting studies of severe congenital malformations to live-born children may introduce substantial bias. In this study, we estimated the attendance to the second-trimester fetal malformation screening program. We also estimated the positive predictive value (PPV) of prenatally assigned International Classification of Disease-10 diagnoses recorded in the Danish National Patient Registry (DNPR) and the completeness of case registration. We used kidney anomalies as an example.
We identified the proportion of all Danish live-born children from January 1, 2007 to December 31, 2012, who were scanned during the second trimester using the DNPR and the Civil Registration System. Details of all fetuses with specific kidney anomaly diagnoses according to the DNPR were retrieved. The PPV was estimated using the nationwide Astraia database of pregnancy medical charts or traditional medical charts, as gold standard. The completeness was assessed using the total number of cases estimated by the capture–recapture method.
Of 372,263 live born infants, 97.3% were scanned during the second trimester. We identified 172 fetuses in the DNPR. Of these, 149 had kidney anomalies according to Astraia or medical chart review, corresponding to a PPV of 87% (95% CI: 81%–91%). The estimated completeness was 43% (95% CI: 38%–49%) for the DNPR and 75% (95% CI: 70%–79%) for Astraia.
Almost all live-born children were scanned during the second trimester in Denmark. However, low completeness may hamper the use of the DNPR for studies of prenatally detected severe malformations, and use of the Astraia database may preferably be considered.
PMCID: PMC4725627  PMID: 26855599
Danish National Patient Registry; International Classification of Disease; validation study; prenatal diagnosis; Astraia; kidney anomaly; Danish Fetal Medicine Database
2.  The Danish National Patient Registry: a review of content, data quality, and research potential 
Clinical Epidemiology  2015;7:449-490.
The Danish National Patient Registry (DNPR) is one of the world’s oldest nationwide hospital registries and is used extensively for research. Many studies have validated algorithms for identifying health events in the DNPR, but the reports are fragmented and no overview exists.
To review the content, data quality, and research potential of the DNPR.
We examined the setting, history, aims, content, and classification systems of the DNPR. We searched PubMed and the Danish Medical Journal to create a bibliography of validation studies. We included also studies that were referenced in retrieved papers or known to us beforehand. Methodological considerations related to DNPR data were reviewed.
During 1977–2012, the DNPR registered 8,085,603 persons, accounting for 7,268,857 inpatient, 5,953,405 outpatient, and 5,097,300 emergency department contacts. The DNPR provides nationwide longitudinal registration of detailed administrative and clinical data. It has recorded information on all patients discharged from Danish nonpsychiatric hospitals since 1977 and on psychiatric inpatients and emergency department and outpatient specialty clinic contacts since 1995. For each patient contact, one primary and optional secondary diagnoses are recorded according to the International Classification of Diseases. The DNPR provides a data source to identify diseases, examinations, certain in-hospital medical treatments, and surgical procedures. Long-term temporal trends in hospitalization and treatment rates can be studied. The positive predictive values of diseases and treatments vary widely (<15%–100%). The DNPR data are linkable at the patient level with data from other Danish administrative registries, clinical registries, randomized controlled trials, population surveys, and epidemiologic field studies – enabling researchers to reconstruct individual life and health trajectories for an entire population.
The DNPR is a valuable tool for epidemiological research. However, both its strengths and limitations must be considered when interpreting research results, and continuous validation of its clinical data is essential.
PMCID: PMC4655913  PMID: 26604824
epidemiological methods; medical record linkage; registries; research design; validation studies
3.  Adiposity in 277 young adult male offspring of women with diabetes compared with controls: A Danish population-based cohort study 
To examine the associations of maternal diabetes, overall and stratified according to treatment of diabetes, with weight-related outcomes at the time of military conscription, at age 18–20 years.
Design and setting
Cohort study of 277 Danish male offspring of mothers with recognized pre-gestational or gestational diabetes. As population-based controls we selected 870 men matched from the Civil Registration Office.
Data on weight-related outcomes were retrieved from the Danish military conscription registry.
Main outcome measures
Military rejection due to adiposity and body mass index (BMI) at conscription.
Army rejection rate due to adiposity was 5.8% (n = 16) among 277 diabetes mellitus-exposed men compared with 3.1% (n = 27) in 870 controls (risk difference 2.7 (95% confidence interval (CI) −0.3–5.7)) and mean BMI at conscription was 1.4 kg/m2 (95%CI 0.8–2.0) higher among those diabetes mellitus-exposed men. In analyses adjusted for birthweight and gestational age, compared with controls, the BMI was 0.6 kg/m2 (95%CI −0.3–1.5) higher in sons of mothers with pre-gestational and 2.7 kg/m2 (95% (CI): 0.9–4.5) higher with gestational diabetes. The greatest BMI difference was in offspring of mothers with gestational diabetes in whom insulin was initiated during pregnancy. We found no difference in conscript height.
Compared with controls, male offspring of women with diabetes had a higher rejection rate due to adiposity and higher adult BMI. Subgroup analyses showed that the association was most pronounced in sons of mothers with gestational diabetes, whereas pre-gestational diabetes was only weakly associated with higher offspring BMI.
PMCID: PMC4643653  PMID: 22486385
Adiposity; conscription; male; maternal diabetes; offspring body mass index
4.  Useful Interplay Between Spontaneous ADR Reports and Electronic Healthcare Records in Signal Detection 
Drug Safety  2015;38(12):1201-1210.
Background and Objective
Spontaneous reporting systems (SRSs) remain the cornerstone of post-marketing drug safety surveillance despite their well-known limitations. Judicious use of other available data sources is essential to enable better detection, strengthening and validation of signals. In this study, we investigated the potential of electronic healthcare records (EHRs) to be used alongside an SRS as an independent system, with the aim of improving signal detection.
A signal detection strategy, focused on a limited set of adverse events deemed important in pharmacovigilance, was performed retrospectively in two data sources—(1) the Exploring and Understanding Adverse Drug Reactions (EU-ADR) database network and (2) the EudraVigilance database—using data between 2000 and 2010. Five events were considered for analysis: (1) acute myocardial infarction (AMI); (2) bullous eruption; (3) hip fracture; (4) acute pancreatitis; and (5) upper gastrointestinal bleeding (UGIB). Potential signals identified in each system were verified using the current published literature. The complementarity of the two systems to detect signals was expressed as the percentage of the unilaterally identified signals out of the total number of confirmed signals. As a proxy for the associated costs, the number of signals that needed to be reviewed to detect one true signal (number needed to detect [NND]) was calculated. The relationship between the background frequency of the events and the capability of each system to detect signals was also investigated.
The contribution of each system to signal detection appeared to be correlated with the background incidence of the events, being directly proportional to the incidence in EU-ADR and inversely proportional in EudraVigilance. EudraVigilance was particularly valuable in identifying bullous eruption and acute pancreatitis (71 and 42 % of signals were correctly identified from the total pool of known associations, respectively), while EU-ADR was most useful in identifying hip fractures (60 %). Both systems contributed reasonably well to identification of signals related to UGIB (45 % in EudraVigilance, 40 % in EU-ADR) but only fairly for signals related to AMI (25 % in EU-ADR, 20 % in EudraVigilance). The costs associated with detection of signals were variable across events; however, it was often more costly to detect safety signals in EU-ADR than in EudraVigilance (median NNDs: 7 versus 5).
An EHR-based system may have additional value for signal detection, alongside already established systems, especially in the presence of adverse events with a high background incidence. While the SRS appeared to be more cost effective overall, for some events the costs associated with signal detection in the EHR might be justifiable.
Electronic supplementary material
The online version of this article (doi:10.1007/s40264-015-0341-5) contains supplementary material, which is available to authorized users.
PMCID: PMC4659852  PMID: 26370104
5.  Apgar-score in children prenatally exposed to antiepileptic drugs: a population-based cohort study 
BMJ Open  2015;5(9):e007425.
It is unknown if prenatal exposure to antiepileptic drugs (AEDs) increases the risk of low Apgar score in offspring.
Population-based study using health registers in Denmark.
We identified all 677 021 singletons born in Denmark from 1997 to 2008 and linked the Apgar score from the Medical Birth Register with information on the women's prescriptions for AEDs during pregnancy from the Danish Register of Medicinal Product Statistics. We used the Danish National Hospital Registry to identify mothers diagnosed with epilepsy before birth of the child. Results were adjusted for smoking and maternal age.
Among 2906 children exposed to AEDs, 55 (1.9%) were born with an Apgar score ≤7 as compared with 8797 (1.3%) children among 674 115 pregnancies unexposed to AEDs (adjusted relative risk (aRR)=1.41 (95% CI 1.07 to 1.85). When analyses were restricted to the 2215 children born of mothers with epilepsy, the aRR of having a low Apgar score associated with AED exposure was 1.34 (95% CI 0.90 to 2.01) When assessing individual AEDs, we found increased, unadjusted RR for exposure to carbamazepine (RR=1.86 (95% CI 1.01 to 3.42)), valproic acid (RR=1.85 (95% CI 1.04 to 3.30)) and topiramate (RR=2.97 (95% CI 1.26 to 7.01)) when compared to unexposed children.
Prenatal exposure to AEDs was associated with increased risk of being born with a low Apgar score, but the absolute risk of a low Apgar score was <2%. Risk associated with individual AEDs indicate that the increased risk is not a class effect, but that there may be particularly high risks of a low Apgar score associated with certain AEDs.
PMCID: PMC4567672  PMID: 26359281
6.  Nuclear Localization of the DNA Repair Scaffold XRCC1: Uncovering the Functional Role of a Bipartite NLS 
Scientific Reports  2015;5:13405.
We have characterized the nuclear localization signal (NLS) of XRCC1 structurally using X-ray crystallography and functionally using fluorescence imaging. Crystallography and binding studies confirm the bipartite nature of the XRCC1 NLS interaction with Importin α (Impα) in which the major and minor binding motifs are separated by >20 residues, and resolve previous inconsistent determinations. Binding studies of peptides corresponding to the bipartite NLS, as well as its major and minor binding motifs, to both wild-type and mutated forms of Impα reveal pronounced cooperative binding behavior that is generated by the proximity effect of the tethered major and minor motifs of the NLS. The cooperativity stems from the increased local concentration of the second motif near its cognate binding site that is a consequence of the stepwise binding behavior of the bipartite NLS. We predict that the stepwise dissociation of the NLS from Impα facilitates unloading by providing a partially complexed intermediate that is available for competitive binding by Nup50 or the Importin β binding domain. This behavior provides a basis for meeting the intrinsically conflicting high affinity and high flux requirements of an efficient nuclear transport system.
PMCID: PMC4548243  PMID: 26304019
7.  The impact of preadmission oral bisphosphonate use on 30-day mortality following stroke: a population-based cohort study of 100,043 patients 
Clinical Epidemiology  2015;7:381-389.
Bisphosphonate use has been associated with increased risk of fatal stroke. We examined the association between preadmission use of oral bisphosphonates and 30-day mortality following hospitalization for stroke.
Patients and methods
We conducted a nationwide population-based cohort study using medical databases and identified all patients in Denmark with a first-time hospitalization for stroke between 1 July 2004 and 31 December 2012 (N=100,043). Cox regression was used to compute adjusted hazard ratios as a measure of 30-day mortality rate ratios (MRRs) associated with bisphosphonate current use (prescription filled within 90 days prior to the stroke) or recent use (prescription filled in the 90–180 days prior to the stroke). Current use was further classified as new or long-term use.
We found 51,982 patients with acute ischemic stroke (AIS), 11,779 with intracerebral hemorrhage (ICH), 4,528 with subarachnoid hemorrhage (SAH), and 31,754 with unspecified stroke. Absolute 30-day mortality risks were increased among current vs nonusers of bisphosphonates for AIS (11.9% vs 8.5%), ICH (43.2% vs 34.5%), SAH (40.3% vs 23.2%), and unspecified strokes (18.8% vs 14.0%). However, in adjusted analyses, current bisphosphonate use did not increase 30-day mortality from AIS (MRR, 0.87; 95% confidence interval [CI]: 0.75, 1.01); ICH (MRR, 1.05; 95% CI: 0.90, 1.23); SAH (MRR, 1.15; 95% CI: 0.83, 1.61); or unspecified stroke (MRR, 0.94; 95% CI: 0.81, 1.09). Likewise, no association with mortality was found for recent use. Adjusted analyses by type of bisphosphonate showed increased mortality following stroke among new users of etidronate (MRR, 1.40; 95% CI: 1.01, 1.93) and reduced mortality after AIS among current users of alendronate (MRR, 0.87; 95% CI: 0.74, 1.02).
We found no overall evidence that preadmission bisphosphonate use increases 30-day mortality following stroke.
PMCID: PMC4554427  PMID: 26346502
prognosis; oral bisphosphonates; stroke; mortality; cardiovascular disease; osteoporosis treatment
8.  Prenatal Valproate Exposure and Risk of Autism Spectrum Disorders and Childhood Autism 
JAMA  2013;309(16):1696-1703.
Valproate is used for the treatment of epilepsy and other neuropsychological disorders and may be the only treatment option for women of childbearing potential. However, prenatal exposure to valproate may increase the risk of autism.
To determine whether prenatal exposure to valproate is associated with an increased risk of autism in offspring.
Design, Setting, and Participants
Population-based study of all children born alive in Denmark from 1996 to 2006. National registers were used to identify children exposed to valproate during pregnancy and diagnosed with autism spectrum disorders (childhood autism [autistic disorder], Asperger syndrome, atypical autism, and other or unspecified pervasive developmental disorders). We analyzed the risks associated with all autism spectrum disorders as well as childhood autism. Data were analyzed by Cox regression adjusting for potential confounders (maternal age at conception, paternal age at conception, parental psychiatric history, gestational age, birth weight, sex, congenital malformations, and parity). Children were followed up from birth until the day of autism spectrum disorder diagnosis, death, emigration, or December 31, 2010, whichever came first.
Main Outcomes and Measures
Absolute risk (cumulative incidence) and the hazard ratio (HR) of autism spectrum disorder and childhood autism in children after exposure to valproate in pregnancy.
Of 655 615 children born from 1996 through 2006, 5437 were identified with autism spectrum disorder, including 2067 with childhood autism. The mean age of the children at end of follow-up was 8.84 years (range, 4-14; median, 8.85). The estimated absolute risk after 14 years of follow-up was 1.53% (95% CI, 1.47%- 1.58%) for autism spectrum disorder and 0.48% (95% CI, 0.46%-0.51%) for childhood autism. Overall, the 508 children exposed to valproate had an absolute risk of 4.42% (95% CI, 2.59%-7.46%) for autism spectrum disorder (adjusted HR, 2.9 [95% CI, 1.7-4.9]) and an absolute risk of 2.50% (95% CI, 1.30%-4.81%) for childhood autism (adjusted HR, 5.2 [95% CI, 2.7-10.0]). When restricting the cohort to the 6584 children born to women with epilepsy, the absolute risk of autism spectrum disorder among 432 children exposed to valproate was 4.15% (95% CI, 2.20%-7.81%) (adjusted HR, 1.7 [95% CI, 0.9-3.2]), and the absolute risk of childhood autism was 2.95% (95% CI, 1.42%-6.11%) (adjusted HR, 2.9 [95% CI, 1.4-6.0]) vs 2.44% (95% CI, 1.88%-3.16%) for autism spectrum disorder and 1.02% (95% CI, 0.70%-1.49%) for childhood autism among 6152 children not exposed to valproate.
Conclusions and Relevance
Maternal use of valproate during pregnancy was associated with a significantly increased risk of autism spectrum disorder and childhood autism in the offspring, even after adjusting for maternal epilepsy. For women of childbearing potential who use antiepileptic medications, these findings must be balanced against the treatment benefits for women who require valproate for epilepsy control.
PMCID: PMC4511955  PMID: 23613074
9.  Congenital cerebral palsy and prenatal exposure to self-reported maternal infections, fever, or smoking 
American journal of obstetrics and gynecology  2013;209(4):332.e1-332.e10.
The objective of the study was to investigate the association between maternal self-reported infections, fever, and smoking in the prenatal period and the subsequent risk for congenital cerebral palsy (CP).
We included the 81,066 mothers of singletons born between 1996 and 2003 who participated in the Danish National Birth Cohort. Children were followed up through December 2008. Information on maternal infections, fever, smoking, and other demographic and lifestyle factors during pregnancy were reported by mothers in computer-assisted telephone interviews in early and midgestation. We identified 139 CP cases including 121 cases of spastic CP (sCP) as confirmed by the Danish National Cerebral Palsy Register. Cox proportional hazards regression models were used to estimate adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs).
Self-reported vaginal infections were associated with an increased risk of CP and sCP (aHR, 1.52; 95% CI, 1.04–2.24; and aHR, 1.73; 95% CI, 1.16–2.60, respectively) and particularly untreated vaginal infections were associated with an increased risk of sCP (aHR, 1.95; 95% CI, 1.16–3.26). Fever was associated with the risk of CP (aHR, 1.53; 95% CI, 1.06–2.21). Smoking 10 or more cigarettes per day during pregnancy was also associated with sCP (aHR, 1.80; 95% CI, 1.10–2.94). There was a modest excess in risk for children exposed to both heavy smoking and vaginal infections. No other self-reported infections were significantly associated with CP.
Self-reported vaginal infections, fever, and smoking 10 or more cigarettes per day during pregnancy were associated with a higher risk of overall CP and/or sCP.
PMCID: PMC4512233  PMID: 23791566
congenital cerebral palsy; maternal infections; pregnancy; smoking
10.  Risk of Fetal Death after Treatment with Antipsychotic Medications during Pregnancy 
PLoS ONE  2015;10(7):e0132280.
Antipsychotic medications are increasingly used during pregnancy. Nevertheless, fetal risks are still not fully studied. It is currently unclear whether the antipsychotic treatment might induce a higher risk of fetal death. We aimed to determine if use of antipsychotic medication during pregnancy is associated with an increased risk of spontaneous abortion or stillbirth.
In a historical cohort study, we identified all clinically recognized pregnancies registered in the nationwide Danish registries from 1997 to 2008 (N = 1,005,319). Exposure was defined as any prescription of antipsychotic medications redeemed by the pregnant women during the exposure window, and recorded in the Danish National Prescription Register. Outcome was defined as any spontaneous abortion or stillbirth recorded in the Danish National Hospital Register and the Danish Medical Birth Register respectively.
Women exposed to antipsychotic medications during pregnancy had a 34% higher risk of spontaneous abortion (adjusted relative risk = 1.34; 95% confidence interval = 1.22; 1.46) compared to unexposed women, but a similar risk compared to women exposed prior to (but not during) pregnancy (adjusted relative risk = 1.04; 95% confidence interval = 0.93; 1.17). The risk of spontaneous abortion was not increased in exposed pregnancies when compared to unexposed pregnancies in the same women (adjusted hazard ratio = 1.11; 95% CI = 0.94; 1.31). A twofold higher risk of stillbirth was found in women exposed to antipsychotic medications compared with unexposed women (relative risk = 2.27; 95% confidence interval = 1.45; 3.55) and compared with women exposed only prior to pregnancy (relative risk = 2.06; 95% confidence interval = 1.01; 4.19).
The increased risk of spontaneous abortion found in women treated with antipsychotic medications during pregnancy is most likely due to confounding factors. The risk of stillbirth was twofold higher in pregnancies exposed to antipsychotic medication during pregnancy. Treatment with antipsychotic medications during pregnancy requires careful consideration.
PMCID: PMC4498617  PMID: 26162087
11.  Characterization of an anti-Bla g 1 scFv: Epitope mapping and cross-reactivity 
Molecular immunology  2014;59(2):200-207.
Bla g 1 is a major allergen from Blatella germanica and one of the primary allergens used to assess cockroach allergen exposure. The epitope of an anti-Bla g 1 scFv was mapped in order to better understand cross reactivity with other group 1 cockroach allergens and patient IgE epitopes. X-ray crystallography was used to determine the structure of the scFv. The scFv epitope on Bla g 1 was located by alanine scanning site-directed mutagenesis and ELISA. Twenty-six rBla g 1-GST alanine mutants were evaluated for variations in binding to the scFv compared to the wild type allergen. Six mutants showed a significant difference in scFv binding affinity. These mutations clustered to form a discontinuous epitope mainly comprising two helices of Bla g 1. The allergen-scFv complex was modeled based on the results, and the epitope region was found to have low sequence similarity with Per a 1, especially among the residues identified as functionally important for the scFv binding to Bla g 1. Indeed, the scFv failed to bind Per a 1 in American cockroach extract. The scFv was unable to inhibit the binding of IgE antibodies from a highly cockroach allergic patient to Bla g 1. Based on the surface area of Bla g 1 occluded by the scFv, putative regions of patient IgE–Bla g 1 interactions can be inferred. This scFv could be best utilized as a capture antibody in an IgE detection ELISA, or to differentiate Bla g 1 from Per a 1 in environmental exposure assays.
PMCID: PMC4097036  PMID: 24667070
Allergen; Structure; Bla g 1; scFv; Cockroach; Epitope
12.  Disproportionate Fetal Growth and the Risk for Congenital Cerebral Palsy in Singleton Births 
PLoS ONE  2015;10(5):e0126743.
To investigate the association between proportionality of fetal and placental growth measured at birth and the risk for congenital cerebral palsy (CP).
Study Design
We identified all live-born singletons born in Denmark between 1995 and 2003 and followed them from 1 year of age until December 31st, 2008. Information on four indices of fetal growth: ponderal index, head circumference/ abdominal circumference ratio, cephalization index and birth weight/ placenta weight ratio was collected. Cox proportional hazards regression models were used to estimate adjusted hazard ratios (aHR) and 95% confidence intervals (CI). All measurements were evaluated as gestational age and sex specific z-scores and in z-score percentile groups, adjusted for potential confounders, and stratified on gestational age groups (<32, 32-36, 37-38, 39, 40, ≥41 weeks).
We identified 503,784 singleton births, of which 983 were confirmed cases of CP. Head/ abdominal circumference ratio (aHR:1.12; 95%CI:1.07-1.16) and cephalization index (aHR:1.14; 95%CI:1.11-1.16) were associated with the risk of CP irrespective of gestational age. Birth weight-placental weight ratio was also associated with CP in the entire cohort (aHR:0.90; 95%CI:0.83-0.97). Ponderal index had a u-shaped association with CP, where both children with low and high ponderal index were at higher risk of CP.
CP is associated with disproportions between birth weight, birth length, placental weight and head circumference suggesting pre and perinatal conditions contribute to fetal growth restriction in children with CP.
PMCID: PMC4431832  PMID: 25974407
13.  The Danish National Prescription Registry in studies of a biological pharmaceutical: palivizumab – validation against two external data sources 
Clinical Epidemiology  2015;7:305-312.
National prescription databases are important tools in pharmacoepidemiological studies investigating potential long-term adverse events after drug use. Palivizumab is a biological pharmaceutical used as passive prophylaxis against severe infection with respiratory syncytial virus in high-risk children.
To assess the registration of palivizumab in the Danish National Prescription Registry (DNPR) and to examine if palivizumab reimbursement data obtained from the Danish Health and Medicines Authority could serve as a supplement to data from the DNPR.
Registration of palivizumab exposure in the DNPR between 1999 and 2010 was compared to two external data sources: registration of palivizumab exposure in medical records, and palivizumab reimbursement data.
During the study period, 182 children with palivizumab exposure were registered in the DNPR. A total of 207 children were registered for palivizumab reimbursement. The sensitivity of palivizumab registration in the DNPR was 26% (20%–34%), and the specificity of no palivizumab registration in the DNPR was 97% (94%–99%), with data from the medical record as the reference. Palivizumab registration sensitivity in reimbursement data was 29% (22%–36%), and the specificity of no palivizumab registration in the DNPR was 97% (94%–99%), with data from the medical record as the reference.
Exposure to palivizumab was underestimated in the DNPR. Reimbursement data are a readily accessible data supplement, which only slightly increased the sensitivity of palivizumab registration in the DNPR. Our findings underline the need to improve DNPR information concerning drugs administered in hospitals.
PMCID: PMC4431470  PMID: 26056490
drug; health register; medical records; respiratory syncytial virus; validation
14.  Structure–Function Studies of DNA Polymerase λ 
Biochemistry  2014;53(17):2781-2792.
DNA polymerase λ (pol λ) functions in DNA repair with its main roles considered to be filling short gaps during repair of double-strand breaks by nonhomologous end joining and during base excision repair. As indicated by structural and biochemical studies over the past 10 years, pol λ shares many common properties with other family X siblings (pol β, pol μ, and terminal deoxynucleotidyl transferase) but also has unique structural features that determine its specific functions. In this review, we consider how structural studies over the past decade furthered our understanding of the behavior and biological roles of pol λ.
PMCID: PMC4018081  PMID: 24716527
15.  Impact of cardiovascular risk factors and medication use on the efficacy of remote ischaemic conditioning: post hoc subgroup analysis of a randomised controlled trial 
BMJ Open  2015;5(4):e006923.
Remote ischaemic conditioning (RIC) promotes cardioprotection in patients undergoing primary percutaneous coronary intervention (pPCI) for ST-elevation myocardial infarction (STEMI). The effect of RIC may be modified by cardiovascular risk factors and their medications. We examined whether cardiovascular risk factors, lipid and glucose levels, and medication use influenced the efficacy of RIC in patients with STEMI treated with pPCI.
Post hoc subgroup analysis of a single-centre randomised controlled trial.
A total of 139 patients with STEMI, randomised during ambulance transport to hospital for pPCI with (n=71) or without (n=68) RIC, met the trial criteria and achieved data for a myocardial salvage index (MSI).
RIC was administered through intermittent arm ischaemia with four cycles of 5 min inflation and 5 min deflation of a blood pressure cuff.
Primary outcome measures
MSI, estimated by single-photon emission CT. We evaluated the efficacy of RIC on the MSI in patient subgroups of cardiovascular risk factors, lipid and glucose levels, and medication use.
We found no significant difference in the efficacy of RIC in subgroups of cardiovascular risk factors, lipid and glucose levels, and medication use. However, point estimates indicated a reduced effect of RIC among smokers (median difference in MSI between RIC and control groups: −0.02 (95% CI −0.32 to 0.28) in smokers vs 0.25 (95% CI 0.08 to 0.42) in non-smokers, p value for interaction=0.13) and an increased effect of RIC in statin users (median difference in MSI between RIC and control groups: 0.34 (95% CI 0.03 to 0.65) in statin users vs 0.09 (95% CI −0.11 to 0.29) in non-statin users, p value for interaction=0.19).
RIC as an adjunct to pPCI seems to improve MSI in our trial population of patients with STEMI regardless of most cardiovascular risk factors and their medications. Our post hoc finding on a limited sample size calls for further investigation in large-scale multicentre trials.
Trial registration number
PMCID: PMC4390720  PMID: 25838505
16.  Immunostimulant patches containing Escherichia coli LT enhance immune responses to DNA- and recombinant protein-based Alzheimer’s disease vaccines 
Journal of neuroimmunology  2014;268(0):50-57.
Immunotherapeutic approaches to treating Alzheimer’s disease (AD) using vaccination strategies must overcome the obstacle of achieving adequate responses to vaccination in the elderly. Here we demonstrate for the first time that application of the E. coli heat-labile enterotoxin adjuvant-laden immunostimulatory patches (LT-IS) dramatically enhances the onset and magnitude of immune responses to DNA- and protein-based vaccines for Alzheimer’s disease following intradermal immunization via gene gun and conventional needles, respectively. Our studies suggest that the immune activation mediated by LT-IS offers improved potency for generating AD-specific vaccination responses that should be investigated as an adjuvant in the clinical arena.
PMCID: PMC3951952  PMID: 24507620
Alzheimer’s disease; epitope vaccine; immunostimulatory patch; immune responses
17.  Impact of preadmission treatment with calcium channel blockers or beta blockers on short-term mortality after stroke: a nationwide cohort study 
BMC Neurology  2015;15:24.
The prognostic impact of preadmission use of calcium channel blockers (CCBs) and beta blockers (BBs) on stroke mortality remains unclear. We aimed to examine whether preadmission use of CCBs or BBs was associated with improved short-term mortality following ischemic stroke, intracerebral hemorrhage (ICH), or subarachnoid hemorrhage (SAH).
We conducted a nationwide population-based cohort study using Danish medical registries. We identified all patients with a first-time inpatient diagnosis of stroke between 2004 and 2012 and their comorbidities. We defined CCB/BB use as current use, former use, or non-use. Current use was further classified as new or long-term use. We used Cox regression modeling to compute 30-day mortality rate ratios (MRRs) with 95% confidence intervals (CIs), controlling for potential confounders.
We identified 100,043 patients with a first-time stroke. Of these, 83,736 (83.7%) patients had ischemic stroke, 11,779 (11.8%) had ICH, and 4,528 (4.5%) had SAH. Comparing current users of CCBs or BBs with non-users, we found no association with mortality for ischemic stroke [adjusted 30-day MRR = 0.99 (95% CI: 0.94-1.05) for CCBs and 1.01 (95% CI: 0.96-1.07) for BBs], ICH [adjusted 30-day MRR = 1.05 (95% CI: 0.95-1.16) for CCBs and 0.95 (95% CI: 0.87-1.04) for BBs], or SAH [adjusted 30-day MRR = 1.05 (95% CI: 0.85-1.29) for CCBs and 0.89 (95% CI: 0.72-1.11) for BBs]. Former use of CCBs or BBs was not associated with mortality.
Preadmission use of CCBs or BBs was not associated with 30-day mortality following ischemic stroke, ICH, or SAH.
Electronic supplementary material
The online version of this article (doi:10.1186/s12883-015-0279-3) contains supplementary material, which is available to authorized users.
PMCID: PMC4365558  PMID: 25884780
Beta-blocker; Calcium channel blocker; Stroke; Ischemic stroke; Hemorrhagic stroke; Mortality
18.  Sustained active site rigidity during synthesis by human DNA polymerase μ 
DNA polymerase mu (Pol μ) is the only template-dependent human DNA polymerase capable of repairing double strand DNA breaks (DSBs) with unpaired 3′-ends in non-homologous end joining (NHEJ). To probe this function, we structurally characterized Pol μ’s catalytic cycle for single nucleotide incorporation. These structures indicate that, unlike other template-dependent DNA polymerases, there are no large-scale conformational changes in protein subdomains, amino acid side chains, or DNA upon dNTP binding or catalysis. Instead, the only major conformational change is seen earlier in the catalytic cycle, when the flexible Loop1 region repositions upon DNA binding. Pol μ variants with changes in Loop1 have altered catalytic properties and are partially defective in NHEJ. The results indicate that specific Loop1 residues contribute to Pol μ’s unique ability to catalyze template-dependent NHEJ of DSBs with unpaired 3′-ends.
PMCID: PMC4164209  PMID: 24487959
Family X DNA polymerase; nonhomologous end joining; DNA double strand break repair; Loop1
19.  Diversity Outbred Mice Identify Population-Based Exposure Thresholds and Genetic Factors that Influence Benzene-Induced Genotoxicity 
Environmental Health Perspectives  2014;123(3):237-245.
Inhalation of benzene at levels below the current exposure limit values leads to hematotoxicity in occupationally exposed workers.
We sought to evaluate Diversity Outbred (DO) mice as a tool for exposure threshold assessment and to identify genetic factors that influence benzene-induced genotoxicity.
We exposed male DO mice to benzene (0, 1, 10, or 100 ppm; 75 mice/exposure group) via inhalation for 28 days (6 hr/day for 5 days/week). The study was repeated using two independent cohorts of 300 animals each. We measured micronuclei frequency in reticulocytes from peripheral blood and bone marrow and applied benchmark concentration modeling to estimate exposure thresholds. We genotyped the mice and performed linkage analysis.
We observed a dose-dependent increase in benzene-induced chromosomal damage and estimated a benchmark concentration limit of 0.205 ppm benzene using DO mice. This estimate is an order of magnitude below the value estimated using B6C3F1 mice. We identified a locus on Chr 10 (31.87 Mb) that contained a pair of overexpressed sulfotransferases that were inversely correlated with genotoxicity.
The genetically diverse DO mice provided a reproducible response to benzene exposure. The DO mice display interindividual variation in toxicity response and, as such, may more accurately reflect the range of response that is observed in human populations. Studies using DO mice can localize genetic associations with high precision. The identification of sulfotransferases as candidate genes suggests that DO mice may provide additional insight into benzene-induced genotoxicity.
French JE, Gatti DM, Morgan DL, Kissling GE, Shockley KR, Knudsen GA, Shepard KG, Price HC, King D, Witt KL, Pedersen LC, Munger SC, Svenson KL, Churchill GA. 2015. Diversity Outbred mice identify population-based exposure thresholds and genetic factors that influence benzene-induced genotoxicity. Environ Health Perspect 123:237–245;
PMCID: PMC4348743  PMID: 25376053
20.  Adverse pregnancy outcomes after exposure to methylphenidate or atomoxetine during pregnancy 
Clinical Epidemiology  2015;7:139-147.
To determine if prenatal exposure to methylphenidate (MPH) or atomoxetine (ATX) increases the risk of adverse pregnancy outcomes in women with attention deficit/hyperactivity disorder (ADHD).
Materials and methods
This was a population-based cohort study of all pregnancies in Denmark from 1997 to 2008. Information on use of ADHD medication, ADHD diagnosis, and pregnancy outcomes was obtained from nationwide registers.
We identified 989,932 pregnancies, in which 186 (0.02%) women used MPH/ATX and 275 (0.03%) women had been diagnosed with ADHD but who did not take MPH/ATX. Our reference pregnancies had no exposure to MPH/ATX and no ADHD diagnosis. Exposure to MPH/ATX was associated with an increased risk of spontaneous abortion (SA; ie, death of an embryo or fetus in the first 22 weeks of gestation) (adjusted relative risk [aRR] 1.55, 95% confidence interval [CI] 1.03–2.36). The risk of SA was also increased in pregnancies where the mother had ADHD but did not use MPH/ATX (aRR 1.56, 95% CI 1.11–2.20). The aRR of Apgar scores <10 was increased among exposed women (aRR 2.06, 95% CI 1.11–3.82) but not among unexposed women with ADHD (aRR 0.99, 95% CI 0.48–2.05).
MPH/ATX was associated with a higher risk of SA, but our study indicated that it may at least partly be explained by confounding by indication. Treatment with MPH/ATX was however associated with low Apgar scores <10, an association not found among women with ADHD who did not use MPH/ATX.
PMCID: PMC4317061  PMID: 25657597
attention deficit/hyperactivity disorder; ADHD; methylphenidate; atomoxetine; pregnancy outcomes
21.  The Western Denmark Cardiac Computed Tomography Registry: a review and validation study 
Clinical Epidemiology  2014;7:53-64.
As a subregistry to the Western Denmark Heart Registry (WDHR), the Western Denmark Cardiac Computed Tomography Registry (WDHR-CCTR) is a clinical database established in 2008 to monitor and improve the quality of cardiac computed tomography (CT) in Western Denmark.
We examined the content, data quality, and research potential of the WDHR-CCTR.
We retrieved 2008–2012 data to examine the 1) content; 2) completeness of procedure registration using the Danish National Patient Registry as reference; 3) completeness of variable registration comparing observed vs expected numbers; and 4) positive predictive values as well as negative predictive values of 19 main patient and procedure variables.
By December 31, 2012, almost 22,000 cardiac CTs with up to 40 variables for each procedure have been registered. Of these, 87% were coronary CT angiography performed in patients with symptoms indicative of coronary artery disease. Compared with the Danish National Patient Registry, the overall procedure completeness was 72%. However, an additional medical record review of 282 patients registered in the Danish National Patient Registry, but not in the WDHR-CCTR, showed that coronary CT angiographies accounted for only 23% of all nonregistered cardiac CTs, indicating >90% completeness of coronary CT angiographies in the WDHR-CCTR. The completeness of individual variables varied substantially (range: 0%–100%), but was >85% for more than 70% of all variables. Using medical record review of 250 randomly selected patients as reference standard, the positive predictive value for the 19 variables ranged from 89% to 100% (overall 97%), whereas the negative predictive value ranged from 97% to 100% (overall 99%). Stratification by center status showed consistently high positive and negative predictive values for both university (96%/99%) and nonuniversity centers (97%/99%).
WDHR-CCTR provides ongoing prospective registration of all cardiac CTs performed in Western Denmark since 2008. Overall, the registry data have a high degree of completeness and validity, making it a valuable tool for clinical epidemiological research.
PMCID: PMC4317160  PMID: 25657592
coronary computed tomography angiography; database; epidemiology; registries
22.  Novel structure of cockroach allergen Bla g 1 has implications for allergenicity and exposure assessment 
The Journal of allergy and clinical immunology  2013;132(6):10.1016/j.jaci.2013.06.014.
Sensitization to cockroach allergens is a major risk factor for asthma. The cockroach allergen Bla g 1 has multiple repeats of ~100 amino acids, but the fold of the protein and the biological function are unknown.
To determine the structure of Bla g 1, investigate the implications for allergic disease, and standardize cockroach exposure assays.
Natural Bla g 1 and recombinant constructs were compared by ELISA using specific murine IgG and human IgE. The structure of Bla g 1 was determined by X-ray crystallography. Mass spectrometry and NMR were utilized to examine ligand-binding properties of the allergen.
The structure of a recombinant Bla g 1 construct with comparable IgE and IgG reactivity to the natural allergen was solved by X-ray crystallography. The Bla g 1 repeat forms a novel fold with 6 helices. Two repeats encapsulate a large and nearly spherical hydrophobic cavity, defining the basic structural unit. Lipids in the cavity varied depending on the allergen origin. Palmitic, oleic and stearic acids were associated with nBla g 1 from cockroach frass. One Unit of Bla g 1 was equivalent to 104 ng of allergen.
Bla g 1 has a novel fold with a capacity to bind various lipids, which suggests a digestive function associated with non-specific transport of lipid molecules in cockroaches. Defining the basic structural unit of Bla g 1 facilitates the standardization of assays in absolute units for the assessment of environmental allergen exposure.
PMCID: PMC3844097  PMID: 23915714
Allergen; asthma; Bla g 1; cockroach; structure; ligand-binding proteins; exposure assessment
23.  Structural characterization of the virulence factor nuclease A from Streptococcus agalactiae  
Nuclease A (NucA) is an extracellular nuclease secreted from S. agalactiae and is required for full virulence during infection. Crystal structures and biochemical characterization of NucA mutants reveal possible roles for surface residues in DNA substrate binding and catalysis. These results may serve as a foundation for the design of targeted antibacterial therapeutic compounds.
The group B pathogen Streptococcus agalactiae commonly populates the human gut and urogenital tract, and is a major cause of infection-based mortality in neonatal infants and in elderly or immunocompromised adults. Nuclease A (GBS_NucA), a secreted DNA/RNA nuclease, serves as a virulence factor for S. agalactiae, facilitating bacterial evasion of the human innate immune response. GBS_NucA efficiently degrades the DNA matrix component of neutrophil extracellular traps (NETs), which attempt to kill and clear invading bacteria during the early stages of infection. In order to better understand the mechanisms of DNA substrate binding and catalysis of GBS_NucA, the high-resolution structure of a catalytically inactive mutant (H148G) was solved by X-ray crystallography. Several mutants on the surface of GBS_NucA which might influence DNA substrate binding and catalysis were generated and evaluated using an imidazole chemical rescue technique. While several of these mutants severely inhibited nuclease activity, two mutants (K146R and Q183A) exhibited significantly increased activity. These structural and biochemical studies have greatly increased our understanding of the mechanism of action of GBS_NucA in bacterial virulence and may serve as a foundation for the structure-based drug design of antibacterial compounds targeted to S. agalactiae.
PMCID: PMC4220975  PMID: 25372684
nuclease A; virulence factors; Streptococcus agalactiae
24.  Acromegaly according to the Danish National Registry of Patients: how valid are ICD diagnoses and how do patterns of registration affect the accuracy of registry data? 
Clinical Epidemiology  2014;6:295-299.
The incidence of acromegaly is uncertain, since population-based studies are few. In the absence of a specific acromegaly registry, the Danish National Registry of Patients (DNRP) becomes a potential source of data for studying the epidemiology of acromegaly, by linking all hospital discharge diagnoses to the personal identification numbers of individual Danish inhabitants. The validity of the DNRP with respect to acromegaly, however, remains to be tested. The aim of this study was to validate the International Classification of Diseases (ICD) codes for acromegaly (ICD-8: 25300, 25301. ICD-10: E22.0) as used in the DNRP, and to assess the influence of various registration patterns on the accuracy of registry data.
We identified patients registered with ICD codes for the diagnosis of acromegaly or other pituitary disorders during the period 1991–2009. Data on the institutional origin of each registration and the number of relevant DNRP registrations were recorded, and systematic patient chart reviews were performed to confirm the diagnosis.
In total, 110 cases of acromegaly were confirmed, compared with 275 registered cases, yielding a positive predictive value (PPV) of 40%. When restricting the search to the regional highly specialized department of endocrinology, the PPV increased to 53% with no loss of cases with confirmed acromegaly. With a requirement of at least one, two, or three DNRP registrations, the PPV increased, but with a concurrent loss of confirmed cases.
The DNRP seems to be a useful source for identifying new cases of acromegaly, especially when restricting the search to a relevant regional highly specialized department. The PPV of DNRP data used for this purpose can be increased by including only cases with several registrations. A similar approach may be successfully applied to other rare diseases in which continuity of care is provided by highly specialized departments.
PMCID: PMC4155997  PMID: 25210475
acromegaly; Danish National Registry of Patients; validation; epidemiology; incidence
25.  Enzymatic Redesigning of Biologically Active Heparan Sulfate* 
The Journal of biological chemistry  2005;280(52):42817-42825.
Heparan sulfate carries a wide range of biological activities, regulating blood coagulation, cell differentiation, and inflammatory responses. The sulfation patterns of the polysaccharide are essential for the biological activities. In this study, we report an enzymatic method for the sulfation of multimilligram amounts of heparan sulfate with specific functions using immobilized sulfotransferases combined with a 3′-phosphoadenosine 5′-phosphosulfate regeneration system. By selecting appropriate enzymatic modification steps, an inactive precursor has been converted to the heparan sulfate having three distinct biological activities, associated with binding to antithrombin, fibroblast growth factor-2, and herpes simplex virus envelope glycoprotein D. Because the recombinant sulfotransferases are expressed in bacteria, and the method uses a low cost sulfo donor, it can be readily utilized to synthesize large quantities of anticoagulant heparin drug or other biologically active heparan sulfates.
PMCID: PMC4140617  PMID: 16260789

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