Single-conformation spectroscopy of hydrogen bonding networks: Solvation, synthetic foldamers, and neurodegenerative diseases

The hydrogen bond is one of the most important interactions in natural processes ranging from protein folding to chemical reactions. Two complementary methodologies are applied to understanding this important interaction: top-down and bottom-up. Top-down methods use large molecules, such as proteins, revealing secondary structure information. Bottom-up experiments are performed on small molecules, utilizing high-resolution spectroscopy to reveal underlying quantum mechanical effects. The complexity gap is formed between these two experimental regimes; between large and small molecules; between bulk and individual solvent molecules; between classical mechanics calculations and quantum chemical calculations. This dissertation will focus on the application of gas phase, single-conformation ultraviolet (UV) and infrared (IR) spectroscopies to the study of molecules and clusters in the size and solvation complexity gap, with the goal of bridging the gulf between the two experimental approaches. Single-conformation spectroscopy is perfectly suited to study solvation. Solvent molecules, in many instances water, can be frozen onto the solute in a stepwise manner. Here, we solvate a prototypical flexible bichromophore—1,2-diphenoxyethane (DPOE)—by stepwise addition of water molecules. Single-conformation spectroscopy reveals both the structural perturbations associated with water molecule addition and their effect on DPOE’s pair of closely spaced excited electronic states. These experimental studies provide excellent insight into solvent effects on vibronic and excitonic coupling, and can be used to further develop the models used to describe such processes. Similarly, single-conformation spectroscopy can reveal the effects of conformational flexibility on the innate conformational preferences and hydrogen bonding motifs in peptides. Results obtained from a study of a cyclically constrained γ peptide, γACHC, reveal that increased conformational flexibility can be controlled by synthetic chemists in order to direct folding into pre-programmed secondary structures and that these structures are stabilized with intramolecular rather than intermolecular hydrogen bonds. This theme of conformational flexibility is continued in studies of glutamine containing peptides. Glutamine—with its flexible, hydrogen bond forming sidechain—is intimately involved with neurodegenerative diseases such as Huntington’s disease. Single-conformation studies help reveal the delicate interplay between three different types of hydrogen bonds within the molecule: backbone-backbone, sidechain-backbone, and sidechain-sidechain hydrogen bonds. The importance of these competing hydrogen bonds on the conformational preferences will be discussed both locally and within the larger context of disease pathogenesis

Increasing the etanercept dose in a treat-to-target approach in juvenile idiopathic arthritis:does it help to reach the target? A post-hoc analysis of the BeSt for Kids randomised clinical trial

Background: Etanercept has been studied in doses up to 0.8 mg/kg/week (max 50 mg/week) in juvenile idiopathic arthritis (JIA) patients. In clinical practice higher doses are used off-label, but evidence regarding the relation with outcomes is lacking. We describe the clinical course of JIA-patients receiving high-dose etanercept (1.6 mg/kg/week; max 50 mg/week) in the BeSt for Kids trial. Methods: 92 patients with oligoarticular JIA, RF-negative polyarticular JIA or juvenile psoriatic arthritis were randomised across three treat-to-target arms: (1) sequential DMARD-monotherapy (sulfasalazine or methotrexate (MTX)), (2) combination-therapy MTX + 6 weeks prednisolone and (3) combination therapy MTX + etanercept. In any treatment-arm, patients could eventually escalate to high-dose etanercept alongside MTX 10mg/m2/week. Results: 32 patients received high-dose etanercept (69% female, median age 6 years (IQR 4–10), median 10 months (7–16) from baseline). Median follow-up was 24.6 months. Most clinical parameters improved within 3 months after dose-increase: median JADAS10 from 7.2 to 2.8 (p = 0.008), VAS-physician from 12 to 4 (p = 0.022), VAS-patient/parent from 38.5 to 13 (p = 0.003), number of active joints from 2 to 0.5 (p = 0.12) and VAS-pain from 35.5 to 15 (p = 0.030). Functional impairments (CHAQ-score) improved more gradually and ESR remained stable. A comparable pattern was observed in 11 patients (73% girls, median age 8 (IQR 6–9)) who did not receive high-dose etanercept despite eligibility (comparison group). In both groups, 56% reached inactive disease at 6 months. No severe adverse events (SAEs) occurred after etanercept dose-increase. In the comparison group, 2 SAEs consisting of hospital admission occurred. Rates of non-severe AEs per subsequent patient year follow-up were 2.27 in the high-dose and 1.43 in the comparison group. Conclusions: Escalation to high-dose etanercept in JIA-patients who were treated to target was generally followed by meaningful clinical improvement. However, similar improvements were observed in a smaller comparison group who did not escalate to high-dose etanercept. No SAEs were seen after escalation to high-dose etanercept. The division into the high-dose and comparison groups was not randomised, which is a potential source of bias. We advocate larger, randomised studies of high versus regular dose etanercept to provide high level evidence on efficacy and safety. Trial registration: Dutch Trial Register; NTR1574; 3 December 2008; https://onderzoekmetmensen.nl/en/trial/26585.</p

A comparison of three treatment strategies in recent onset non-systemic Juvenile Idiopathic Arthritis: Initial 3-months results of the BeSt for Kids-study

Background: Combination therapy with prednisone or etanercept may induce earlier and/or more improvement in disease activity in Disease Modifying Anti Rheumatic Drug (DMARD) naïve non-systemic Juvenile Idiopathic Arthritis (JIA) patients. Here we present three months clinical outcome of initial treatments of the BeSt-for-Kids study. Methods: Included patients were randomized to either: 1. initial DMARD-monotherapy (sulfasalazine (SSZ) or methotrexate (MTX)), 2. Initial MTX / prednisolone-bridging, 3. Initial combination MTX/etanercept. Percentage inactive disease, adjusted (a) ACR Pedi30, 50 and 70 and JADAS after 6 and 12 weeks of treatment (intention to treat analysis) and side effects are reported. Results: 94 patients (67% girls, 32 (arm 1), 32 (arm 2) and 30 (arm 3) with median (InterQuartileRange) age of 9.1 (4.7-12.9) years were included. 38% were ANA positive, 10 had oligo-articular disease, 68 polyarticular JIA and 16 psoriatic arthritis. Baseline median (IQR) ACRpedi-scores: VAS physician 49 (40-58) mm, VAS patient 54 (37-70) mm, ESR 6.5 (2-14.8)mm/hr, active joint count 8 (5-12), limited joint count 3 (1-5), CHAQ score 0.88 (0.63-1.5). In arm 1, 17 started with MTX, 15 with SSZ. After 3 months, aACR Pedi 50 was reached by 10/32 (31%), 12/32(38%) and 16/30 (53%) (p = 0.19) and aACR Pedi 70 was reached by 8/32 (25%), 6/32(19%) and 14/30(47%) in arms 1-3 (p = 0.04). Toxicity was similar. Few serious adverse events were reported. Conclusion: After 3 months of treatment in a randomized trial, patients with recent-onset JIA achieved significantly more clinical improvement (aACRPedi70) on initial combination therapy with MTX / etanercept than on initial MTX or SSZ monotherapy. Trial registration:NTR1574. Registered 3 December 2008

Significant pain decrease in children with non-systemic Juvenile Idiopathic Arthritis treated to target:results over 24 months of follow up

Background: The aim of this study was to compare pain-scores in three targeted treatment-strategies in JIA-patients and to identify characteristics predicting persistent pain. Methods: In the BeSt-for-Kids-study 92 DMARD-naïve JIA-patients were randomized in 3 treatment-strategies: 1) initial sequential DMARD-monotherapy 2) initial methotrexate (MTX)/prednisolone-bridging or 3) initial MTX/etanercept. Potential differences in VAS pain scores (0-100 mm) over time between treatment-strategies were compared using linear mixed models with visits clustered within patients. A multivariable model was used to assess the ability of baseline characteristics to predict the chance of high pain-scores during follow-up. Results: Pain-scores over time reduced from mean 55.3 (SD 21.7) to 19.5 (SD 25.3) mm after 24 months. On average, pain-scores decreased significantly with β -1.37 mm (95% CI -1.726; -1.022) per month. No significant difference was found between treatment-strategies (interaction term treatment arm*time (months) β (95% CI) arm 1: 0.13 (-0.36; 0.62) and arm 2: 0.37 (-0.12; 0.86) compared to arm 3). Correction for sex and symptom duration yielded similar results. Several baseline characteristics were predictive for pain over time. Higher VAS pain [β 0.44 (95% CI 0.25; 0.65)] and higher active joint count [0.77 (0.19; 1.34)] were predictive of higher pain over time, whereas, low VAS physician [-0.34 (-0.55; -0.06)], CHQ Physical [-0.42 (-0.72; -0.11)] and Psychosocial summary Score [-0.42 (-0.77; -0.06)] were predictive of lower pain. Conclusions: Treatment-to-target seems effective in pain-reduction in non-systemic JIA-patients irrespective of initial treatment-strategy. Several baseline-predictors for pain over time were found, which could help to identify patients with a high risk for development of chronic pain. Trial registration: Dutch Trial Registry number 1574.</p

Nailfold capillary scleroderma pattern may be associated with disease damage in childhood-onset systemic lupus erythematosus:important lessons from longitudinal follow-up

OBJECTIVES: To observe if capillary patterns in childhood-onset SLE (cSLE) change over time and find associations between a capillary scleroderma pattern with disease activity, damage or scleroderma-like features. METHODS: Clinical and (yearly) capillaroscopy data from a longitudinal cohort of patients with cSLE (minimum of four Systemic Lupus International Collaborating Clinics (SLICC) criteria, onset <18 years) were analysed. Disease activity was measured by Systemic Lupus Erythematosus Activity Index (SLEDAI) and disease damage by SLICC Damage Index. A scleroderma pattern was defined according to the ‘fast track algorithm’ from the European League Against Rheumatism Study Group on Microcirculation in Rheumatic Diseases. An abnormal capillary pattern, not matching a scleroderma pattern, was defined as ‘microangiopathy’. RESULTS: Our cohort consisted of 53 patients with cSLE with a median disease onset of 14 years (IQR 12.5–15.5 years), median SLEDAI score at diagnosis was 11 (IQR 8–16), median SLEDAI at follow-up was 2 (IQR 1–6). A scleroderma pattern (ever) was seen in 18.9%, while only 13.2% of patients had a normal capillary pattern. Thirty-three patients had follow-up capillaroscopy of which 21.2% showed changes in type of capillary pattern over time. Type of capillary pattern was not associated with disease activity. Raynaud’s phenomenon (ever) was equally distributed among patients with different capillaroscopy patterns (p=0.26). Anti-ribonucleoprotein antibodies (ever) were significantly more detected (Χ(2), p=0.016) in the scleroderma pattern subgroup (n=7 of 10, 70%). Already 5 years after disease onset, more than 50% of patients with a scleroderma pattern had SLE-related disease damage (HR 4.5, 95% CI 1.1 to 18.8, p=0.034), but they did not develop clinical features of systemic sclerosis at follow-up. Number of detected fingers with a scleroderma pattern was similar between cSLE, juvenile systemic sclerosis and juvenile undifferentiated connective tissue disease. CONCLUSION: This longitudinal study shows that the majority of capillary patterns in cSLE are abnormal and they can change over time. Irrespective of disease activity, a capillary scleroderma pattern in cSLE may be associated with higher risk of SLE-related disease damage

A study protocol of external validation of eight COVID-19 prognostic models for predicting mortality risk in older populations in a hospital, primary care, and nursing home setting

BACKGROUND: The COVID-19 pandemic has a large impact worldwide and is known to particularly affect the older population. This paper outlines the protocol for external validation of prognostic models predicting mortality risk after presentation with COVID-19 in the older population. These prognostic models were originally developed in an adult population and will be validated in an older population (≥ 70 years of age) in three healthcare settings: the hospital setting, the primary care setting, and the nursing home setting.METHODS: Based on a living systematic review of COVID-19 prediction models, we identified eight prognostic models predicting the risk of mortality in adults with a COVID-19 infection (five COVID-19 specific models: GAL-COVID-19 mortality, 4C Mortality Score, NEWS2 + model, Xie model, and Wang clinical model and three pre-existing prognostic scores: APACHE-II, CURB65, SOFA). These eight models will be validated in six different cohorts of the Dutch older population (three hospital cohorts, two primary care cohorts, and a nursing home cohort). All prognostic models will be validated in a hospital setting while the GAL-COVID-19 mortality model will be validated in hospital, primary care, and nursing home settings. The study will include individuals ≥ 70 years of age with a highly suspected or PCR-confirmed COVID-19 infection from March 2020 to December 2020 (and up to December 2021 in a sensitivity analysis). The predictive performance will be evaluated in terms of discrimination, calibration, and decision curves for each of the prognostic models in each cohort individually. For prognostic models with indications of miscalibration, an intercept update will be performed after which predictive performance will be re-evaluated.DISCUSSION: Insight into the performance of existing prognostic models in one of the most vulnerable populations clarifies the extent to which tailoring of COVID-19 prognostic models is needed when models are applied to the older population. Such insight will be important for possible future waves of the COVID-19 pandemic or future pandemics.</p

Endothelial and Inflammation Biomarker Profiles at Diagnosis Reflecting Clinical Heterogeneity and Serving as a Prognostic Tool For Treatment Response in Two Independent Cohorts of Patients With Juvenile Dermatomyositis

Objective: Juvenile dermatomyositis (DM) is a heterogeneous systemic immune-mediated vasculopathy. This study was undertaken to 1) identify inflammation/endothelial dysfunction–related biomarker profiles reflecting disease severity at diagnosis, and 2) establish whether such biomarker profiles could be used for predicting the response to treatment in patients with juvenile DM. Methods: In total, 39 biomarkers related to activation of endothelial

Mutationen im PTS-Gen und mögliche Auswirkungen auf Funktion und Struktur der 6-Pyruvoyl-Tetrahydropterin-Synthase

Background: Research on Juvenile Idiopathic Arthritis (JIA) should support patients, caregivers/parents (carers) and clinicians to make important decisions in the consulting room and eventually to improve the lives of patients with JIA. Thus far these end-users of JIA-research have rarely been involved in the prioritisation of future research. Main body: Dutch organisations of patients, carers and clinicians will collaboratively develop a research agenda for JIA, following the James Lind Alliance (JLA) methodology. In a 'Priority Setting Partnership' (PSP), they will gradually establish a top 10 list of the most important unanswered research questions for JIA. In this process the input from clinicians, patients and their carers will be equally valued. Additionally, focus groups will be organised to involve young people with JIA. The involvement of all contributors will be monitored and evaluated. In this manner, the project will contribute to the growing body of literature on how to involve young people in agenda setting in a meaningful way. Conclusion: A JIA research agenda established through the JLA method and thus co-created by patients, carers and clinicians will inform researchers and research funders about the most important research questions for JIA. This will lead to research that really matters.</p