Development and validation of a prediction model for incident hand osteoarthritis in the HUNT study.

OBJECTIVE: To develop and externally validate prediction models for incident hand osteoarthritis (OA) in a large population-based cohort of middle aged and older men and women. DESIGN: We included 17,153 men and 18,682 women from a population-based cohort, aged 35-70 years at baseline (1995-1997). Incident hand OA were obtained from diagnostic codes in the Norwegian National Patient Register (1995-2018). We studied whether a range of self-reported and clinically measured predictors could predict hand OA, using the Area Under the receiver-operating Curve (AUC) from logistic regression. External validation of an existing prediction model for male hand OA was tested on discrimination in a sample of men. Bootstrapping was used to avoid overfitting. RESULTS: The model for men showed modest discriminatory ability (AUC = 0.67, 95% CI 0.62-0.71). Adding a genetic risk score did not improve prediction. Similar discrimination was observed in the model for women (AUC = 0.62, 95% CI 0.59-0.64). Prediction was not improved by adding a genetic risk score or hormonal and reproductive factors. Applying external validation, similar results were observed among men in HUNT (The Nord-Trøndelag Health Study) as in the developmental sample (AUC = 0.62, 95% CI 0.57-0.65). CONCLUSION: We developed prediction models for incident hand OA in men and women. For women, the model included body mass index (BMI), heavy physical work, high physical activity and perceived poor health. The model showed moderate discrimination. For men, we have shown that a prediction model including BMI, education and information on sleep can predict incident hand OA in several populations with moderate discriminative ability.

The causal role of smoking on the risk of hip or knee replacement due to primary osteoarthritis: a Mendelian randomisation analysis of the HUNT study.

OBJECTIVE: Smoking has been associated with a reduced risk of hip and knee osteoarthritis (OA) and subsequent joint replacement. The aim of the present study was to assess whether the observed association is likely to be causal. METHOD: 55,745 participants of a population-based cohort were genotyped for the rs1051730 C > T single-nucleotide polymorphism (SNP), a proxy for smoking quantity among smokers. A Mendelian randomization analysis was performed using rs1051730 as an instrument to evaluate the causal role of smoking on the risk of hip or knee replacement (combined as total joint replacement (TJR)). Association between rs1051730 T alleles and TJR was estimated by hazard ratios (HRs) and 95% confidence intervals (CIs). All analyses were adjusted for age and sex. RESULTS: Smoking quantity (no. of cigarettes) was inversely associated with TJR (HR 0.97, 95% CI 0.97-0.98). In the Mendelian randomization analysis, rs1051730 T alleles were associated with reduced risk of TJR among current smokers (HR 0.84, 95% CI 0.76-0.98, per T allele), however we found no evidence of association among former (HR 0.97, 95% CI 0.88-1.07) and never smokers (HR 0.97, 95% CI 0.89-1.06). Neither adjusting for body mass index (BMI), cardiovascular disease (CVD) nor accounting for the competing risk of mortality substantially changed the results. CONCLUSION: This study suggests that smoking may be causally associated with the reduced risk of TJR. Our findings add support to the inverse association found in previous observational studies. More research is needed to further elucidate the underlying mechanisms of this causal association.

Exome chip analyses in adult attention deficit hyperactivity disorder.

Attention-deficit/hyperactivity disorder (ADHD) is a highly heritable childhood-onset neuropsychiatric condition, often persisting into adulthood. The genetic architecture of ADHD, particularly in adults, is largely unknown. We performed an exome-wide scan of adult ADHD using the Illumina Human Exome Bead Chip, which interrogates over 250 000 common and rare variants. Participants were recruited by the International Multicenter persistent ADHD CollaboraTion (IMpACT). Statistical analyses were divided into 3 steps: (1) gene-level analysis of rare variants (minor allele frequency (MAF)<1%); (2) single marker association tests of common variants (MAF⩾1%), with replication of the top signals; and (3) pathway analyses. In total, 9365 individuals (1846 cases and 7519 controls) were examined. Replication of the most associated common variants was attempted in 9847 individuals (2077 cases and 7770 controls) using fixed-effects inverse variance meta-analysis. With a Bonferroni-corrected significance level of 1.82E-06, our analyses of rare coding variants revealed four study-wide significant loci: 6q22.1 locus (P=4.46E-08), where NT5DC1 and COL10A1 reside; the SEC23IP locus (P=6.47E-07); the PSD locus (P=7.58E-08) and ZCCHC4 locus (P=1.79E-06). No genome-wide significant association was observed among the common variants. The strongest signal was noted at rs9325032 in PPP2R2B (odds ratio=0.81, P=1.61E-05). Taken together, our data add to the growing evidence of general signal transduction molecules (NT5DC1, PSD, SEC23IP and ZCCHC4) having an important role in the etiology of ADHD. Although the biological implications of these findings need to be further explored, they highlight the possible role of cellular communication as a potential core component in the development of both adult and childhood forms of ADHD.

OS046. Genome-wide association scans identify novel maternalsusceptibility loci for preeclampsia.

INTRODUCTION: We have successfully utilized a family-based study design to localize several positional candidate preeclampsia susceptibility genes to chromosomes 2q22(ACVR2A,LCT,LRP1B,RND3,GCA),5q (ERAP2) and 13q(TNFSF13B). We now report on our continued positional cloning efforts using an alternative genome-wide association (GWA) mapping strategy in large Caucasian case-control cohorts from Australia and Norway. OBJECTIVES: To identify maternal genetic risk loci for preeclampsia. METHODS: The unrelated Australian samples (545 cases,547 controls) were genotyped using Illumina BeadChip technology (700K loci) and have been analyzed using PLINK. All unrelated Norwegian samples were genotyped across several Illumina BeadChip substrates and consist of 847 cases (700K loci) and 638 controls. The Norwegian control samples originate from other HUNT studies pertaining to migraine (n=95,700K loci), lung cancer (n=89,370K loci) and normal brain pathology (n=454,2.5M loci). To analyze a concordant set of 2.5-3 million genotypes across all Norwegian samples we are currently using MaCH to impute those loci not directly genotyped. The Norwegian GWA data will be analyzed in SOLAR utilizing empirical kinship estimates to account for any distant relatedness. RESULTS: 1078 Australian samples (538 cases,540 controls) and 648, 175 SNPs passed our quality control metrics. Two SNP associations (rs7579169,p=3.6×10(-7); rs12711941,p=4.3×10(-7)) satisfied our genome-wide significant threshold (p<5.1×10(-7)). These SNPs reside less than 15kb downstream from the 3 terminus of the Inhibin, beta B (INHBB) gene on 2q14.2. Sequencing of the INHBB locus in our patient cohort identified a third intergenic SNP to significantly associate with preeclampsia (rs7576192,p=1.5×10(-7)). These three SNPs confer risk (OR>1.56) and are in strong linkage disequilibrium with each other (r(2)>0.9) but not with any other genotyped SNP ±200kb. The analysis of the Norwegian GWAS is underway. CONCLUSION: The Australian GWAS has identified a novel preeclampsia risk locus on chromosome 2q. The INHBB gene closest to our SNP associations is a plausible positional candidate susceptibility gene. There is a substantive body of evidence implicating inhibins, activins and other members of the TGF-ßsuperfamily to have a role in the development of preeclampsia. The biological connection between ACVR2A and INHBB leads us to speculate that our linkage-based and GWA-based study designs, respectively, have identified a key biological pathway involved in susceptibility to preeclampsia.

Spectral diffusion and electron-phonon coupling of the B800 BChl a molecules in LH2 complexes from three different species of purple bacteria.

We have investigated the spectral diffusion and the electron-phonon coupling of B800 bacteriochlorophyll a molecules in the peripheral light-harvesting complex LH2 for three different species of purple bacteria, Rhodobacter sphaeroides, Rhodospirillum molischianum, and Rhodopseudomonas acidophila. We come to the conclusion that B800 binding pockets for Rhodobacter sphaeroides and Rhodopseudomonas acidophila are rather similar with respect to the polarity of the protein environment but that the packaging of the alphabeta-polypeptides seems to be less tight in Rb. sphaeroides with respect to the other two species.

Structure and reactivity in the non-mevalonate pathway of isoprenoid biosynthesis.

The function, structure and mechanism of two Escherichia coli enzymes involved in the non-mevalonate route of isoprenoid biosynthesis, 2C-methyl-D-erythritol 4-phosphate cytidylyltransferase and 2C-methyl-D-erythritol 2,4-cyclodiphosphate synthase, are reviewed. Comparisons of each with enzymes from microbial pathogens highlight important conservation of sequence suggestive of similarities in secondary structure, subunit folds, quaternary structure and active sites. Since both enzymes are validated drug targets, the models provide templates for structure-based design of anti-microbial agents targeting a number of serious human diseases.

Distinct binding determinants for ERK2/p38alpha and JNK map kinases mediate catalytic activation and substrate selectivity of map kinase phosphatase-1.

Mitogen-activated protein (MAP) kinase phosphatase 1 (MKP-1/CL100) is an inducible nuclear dual specificity protein phosphatase that can dephosphorylate and inactivate both mitogen- and stress-activated protein kinases in vitro and in vivo. However, the molecular mechanism responsible for the substrate selectivity of MKP-1 is unknown. In addition, it has been suggested that the signal transducers and activators of transcription 1 (STAT1) transcription factor is a physiological non-MAP kinase substrate for MKP-1. We have used the yeast two-hybrid assay to demonstrate that MKP-1 is able to interact selectively with the extracellular signal-regulated kinase 1/2 (ERK1/2), p38alpha, and c-Jun NH(2)-terminal kinase (JNK) MAP kinase isoforms. Furthermore, this binding is accompanied by catalytic activation of recombinant MKP-1 protein in vitro, and these end points show an absolute correlation with MKP-1 substrate selectivity in vivo. In contrast, MKP-1 does not interact with STAT1. Recombinant STAT1 does not cause catalytic activation of MKP-1; nor does MKP-1 block tyrosine phosphorylation of STAT1 in vivo. Both binding and catalytic activation of MKP-1 are abrogated by mutation of a conserved docking site in ERK2, p38alpha, and JNK1 MAP kinases. Within MKP-1, MAP kinase binding is mediated by the amino-terminal noncatalytic domain of the protein. However, mutation of a conserved cluster of positively charged residues within this domain abolishes the binding and activation of MKP-1 by ERK2 and p38alpha but not JNK1, indicating that there are distinct binding determinants for these MAP kinase isoforms. We conclude that the substrate selectivity of MKP-1 is determined by specific protein-protein interactions coupled with catalytic activation of the phosphatase and that these interactions are restricted to members of the MAP kinase family of enzymes.

Acquired thermotolerance and heat shock proteins in thermophiles from the three phylogenetic domains.

Thermophilic organisms from each of the three phylogenetic domains (Bacteria, Archaea, and Eucarya) acquired thermotolerance after heat shock. Bacillus caldolyticus grown at 60 degrees C and heat shocked at 69 degrees C for 10 min showed thermotolerance at 74 degrees C, Sulfolobus shibatae grown at 70 degrees C and heat shocked at 88 degrees C for 60 min showed thermotolerance at 95 degrees C, and Thermomyces lanuginosus grown at 50 degrees C and heat shocked at 55 degrees C for 60 min showed thermotolerance at 58 degrees C. Determinations of protein synthesis during heat shock revealed differences in the dominant heat shock proteins for each species. For B. caldolyticus, a 70-kDa protein dominated while for S. shibatae, a 55-kDa protein dominated and for T. lanuginosus, 31- to 33-kDa proteins dominated. Reagents that disrupted normal protein synthesis during heat shock prevented the enhanced thermotolerance.

Relation of estriol in saliva to serum estriol during normal pregnancy.

As saliva is an easily accessible biological material, compared with 24-hour urine and blood, the salivary concentration of estriol was studied from the 30th to the 41st week of gestation in 268 samples from 124 normal pregnancies. At the same time, venous blood samples were drawn and analyzed for total and unconjugated estriol. The mean values for the concentration of total estriol in saliva in the 30th and 41st weeks were 2.8 and 7.2 nmol/l respectively. The salivary estriol concentration appears to increase in perfect conformity with its serum concentration in the course of gestation. If estriol in saliva also reflects low serum values and an impaired function of the feto-placental unit, analyses of the saliva may be applicable as a screening procedure in high-risk pregnancies.

Analysis of swimming pool accidents resulting in spinal cord injury.

This paper is a summary of a study of 72 cases of swimming-pool accidents resulting in serious injuries with the potential of permanent disability. Sixty-four of the 72 cases resulted in spinal cord injuries, 57 of which involved quadriplegic lesions. The authors observed that the majority of these injuries resulted from a lack of good judgement and common sense rather than from intoxication or pool structural deficiencies. Also of note was the lack of appropriate first-aid and extrication rendered, as well as the absence of uniform treatment and care received by the majority of the patients.