Publications by authors named "Robert Konrad"

Introduction: Tovertafel is a VR-based serious game for dementia care (SGDC) that aims to stimulate residents affected by dementia in nursing homes, promote social and cognitive skills and reduce apathy. The aim of this study is to investigate the effects of using Tovertafel on apathy, social interaction and social activity of people with dementia (PWD) in long-term inpatient care in Germany.

Methods: In this monocentric intervention study, 25 residents of an inpatient long-term care facility with moderate or severe dementia had two weekly applications of Tovertafel over a period of 8 weeks.

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  • * Current tests for measuring Lp(a) often assess total apo(a), which may not accurately reflect Lp(a) levels or the effects of new treatments.
  • * A new immunoassay developed for measuring Lp(a) particles showed better accuracy, indicating that muvalaplin's Lp(a)-lowering effects were previously underestimated by commercial tests, while lepodisiran's effects were consistent across both methods.
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  • Psoriasis, a complicated skin condition linked to inflammation, has unclear connections between its severity, related cytokine levels, and heart disease risk.
  • This study aimed to identify serum markers to help monitor cardiovascular disease (CVD) risk in psoriasis patients by examining relationships between cytokines and coronary artery health.
  • Key findings highlight that specific cytokines (IL-17A, IL-19, IL-36) correlate with psoriasis severity, while markers like CD31 and resistin show promise for tracking coronary atherosclerosis progression, particularly in patients with psoriasis vulgaris.
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  • ANGPTL3/4/8 proteins regulate lipoprotein lipase (LPL) activity, with ANGPTL8 forming complexes that influence ANGPTL4's function; however, their association with cardiovascular outcomes is under-researched.
  • This study involved measuring various ANGPTL proteins and complexes in two large population studies (LURIC and getABI) focusing on cardiovascular health and outcomes over several years.
  • Findings showed that while ANGPTL3/8 inhibited LPL activity and correlated with increased LDL-C and triglycerides, they did not predict cardiovascular death; however, ANGPTL4/8 and CD-ANGPTL4 were linked to higher diabetes prevalence and increased cardiovascular mortality risk.
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Apolipoprotein AV (APOA5) deficiency causes hypertriglyceridemia in mice and humans. For years, the cause remained a mystery, but the mechanisms have now come into focus. Here, we review progress in defining APOA5's function in plasma triglyceride metabolism.

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Background And Aims: Previous studies have derived and validated an HDL apolipoproteomic score (pCAD) that predicts coronary artery disease (CAD) risk. However, the associations between pCAD and markers of cardiometabolic health in healthy adults are not known, nor are the effects of regular exercise on pCAD.

Methods: A total of 641 physically inactive adults free of cardiovascular disease from the HERITAGE Family Study completed 20 weeks of exercise training.

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  • Apolipoprotein AV (APOA5) helps lower fat levels (triglycerides) in the blood by stopping another protein complex (ANGPTL3/8) from interfering with lipoprotein lipase (LPL), which breaks down fats.
  • Researchers found that a mutation in APOA5 leads to higher triglyceride levels, meaning certain parts of the protein are needed to perform its job well.
  • Experiments with mice showed that the normal version of APOA5 worked to reduce triglyceride levels, while a modified version without important parts didn’t, highlighting those parts' key role in keeping fat levels in check.
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  • * The study produced anti-siRNA polyclonal antibodies primarily targeting the N-acetylgalactosamine (GalNAc) component, which can serve as positive controls in immunogenicity assays for GalNAc-conjugated siRNAs.
  • * Additionally, anti-GalNAc monoclonal antibodies showed good sensitivity and drug tolerance, indicating their potential as alternative positive controls, aiding in the development of immunogenicity assays for siRNA therapeutics.
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Angiopoietin-like protein (ANGPTL) complexes 3/8 and 4/8 are established inhibitors of LPL and novel therapeutic targets for dyslipidemia. However, the effects of regular exercise on ANGPTL3/8 and ANGPTL4/8 are unknown. We characterized ANGPTL3/8 and ANGPTL4/8 and their relationship with in vivo measurements of lipase activities and cardiometabolic traits before and after a 5-month endurance exercise training intervention in 642 adults from the HERITAGE (HEalth, RIsk factors, exercise Training And GEnetics) Family Study.

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Purpose Of Review: The angiopoietin-like (ANGPTL) proteins ANGPTL3 and ANGPTL4 are critical lipoprotein lipase (LPL) inhibitors. This review discusses the unique ability of the insulin-responsive protein ANGPTL8 to regulate triglyceride (TG) metabolism by forming ANGPTL3/8 and ANGPTL4/8 complexes that control tissue-specific LPL activities.

Recent Findings: After feeding, ANGPTL4/8 acts locally in adipose tissue, has decreased LPL-inhibitory activity compared to ANGPTL4, and binds tissue plasminogen activator (tPA) and plasminogen to generate plasmin, which cleaves ANGPTL4/8 and other LPL inhibitors.

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Biotherapeutics have the potential to trigger undesired immune responses in the patients. For therapeutic proteins, immunogenicity is manifested as anti-drug antibodies (ADA). Because ADA could compromise pharmacokinetics, efficacy, and safety, regulatory agencies require immunogenicity assessment during clinical development.

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  • Reduced levels of lipoprotein lipase (LPL) in capillaries are suspected to be the cause of hypertriglyceridemia in Apoa5-/- mice, as evidenced by lower LPL staining in heart and brown adipose tissue capillaries.
  • The study found that Apoa5-/- mice had decreased binding of LPL antibodies in these capillaries and lower LPL levels in their postheparin plasma, indicating a disruption in LPL activity.
  • Treatment with an ANGPTL3/8-specific antibody and APOA5 corrected triglyceride levels and LPL levels in these mice, revealing the role of APOA5 in regulating LPL activity and plasma triglyceride metabolism.
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Biologic drugs (therapeutic proteins or peptides) have become one of the most important therapeutic modalities over the past few decades. Drug-induced immunogenicity is a significant concern as it may affect safety, tolerability, and efficacy. With more sensitive and drug-tolerant screening assays in use today, reliable estimation of anti-drug-antibody (ADA) titer has become more important for understanding clinically relevant ADA levels.

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After feeding, adipose tissue lipoprotein lipase (LPL) activity should be maximized, therefore the potent LPL-inhibitory activity of angiopoietin-like protein 4 (ANGPTL4) must be blocked by ANGPTL8 through formation of ANGPTL4/8 complexes. ANGPTL4/8 tightly binds and protects LPL but also partially inhibits its activity. Recently, we demonstrated ANGPTL4/8 also binds tissue plasminogen activator (tPA) and plasminogen to generate plasmin that cleaves ANGPTL4/8 to restore LPL activity.

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Background: Rheumatoid factor (RF) consists of autoantibodies that bind the fragment crystallizable (Fc) region of human immunoglobulin G (IgG) and present in sera of rheumatoid arthritis (RA) patients. Immunoassays to detect antidrug antibodies (ADA) in RA patient samples may experience interference due to RF binding and crosslinking Fc regions of the capture and detection antibody reagents. To overcome this interference, a novel Fab affinity-capture and elution (ACE)-bridging immunoassay (Fab ACE-Bridge) was developed with monovalent-recombinant Fab to avoid RF interference.

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Aims: Apolipoprotein C-II (ApoC-II) is thought to activate lipoprotein lipase (LPL) and is therefore a possible target for treating hypertriglyceridemia. Its relationship with cardiovascular risk has not been investigated in large-scale epidemiologic studies, particularly allowing for apolipoprotein C-III (ApoC-III), an LPL antagonist. Furthermore, the exact mechanism of ApoC-II-mediated LPL activation is unclear.

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Triglyceride (TG) metabolism is highly regulated by angiopoietin-like protein (ANGPTL) family members [Y. Q. Chen ,  , 1203-1220 (2020)].

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Adeno-associated virus (AAV) based gene therapies are gaining significant momentum as a novel therapeutic modality. However, a yet unsolved concern for using AAV as a vector is the high potential to elicit humoral and cellular responses, which are often exacerbated by pre-existing immunity due to exposure to wild type AAV. Therefore, characterization of pre-existing and treatment emergent anti-AAV antibodies is of great importance to the development of AAV based gene therapies.

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Oxyntomodulin (Oxm) is a proglucagon-derived peptide agonist of both the GLP-1 and glucagon receptors and is a key regulator of gastric acid secretion and energy expenditure. Differential processing from proglucagon hinders assay immunoassay selectivity. Antibody engineering was used to develop a sandwich immunoassay that selectively measures endogenous Oxm.

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Triacylglycerol (TG) metabolism is tightly regulated to maintain a pool of TG within circulating lipoproteins that can be hydrolyzed in a tissue-specific manner by lipoprotein lipase (LPL) to enable the delivery of fatty acids to adipose or oxidative tissues as needed. Elevated serum TG concentrations, which result from a deficiency of LPL activity or, more commonly, an imbalance in the regulation of tissue-specific LPL activities, have been associated with an increased risk of atherosclerotic cardiovascular disease through multiple studies. Among the most critical LPL regulators are the angiopoietin-like (ANGPTL) proteins ANGPTL3, ANGPTL4, and ANGPTL8, and a number of different apolipoproteins including apolipoprotein A5 (ApoA5), apolipoprotein C2 (ApoC2), and apolipoprotein C3 (ApoC3).

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Triglycerides (TG) are required for fatty acid transport and storage and are essential for human health. Angiopoietin-like-protein 8 (ANGPTL8) has previously been shown to form a complex with ANGPTL3 that increases circulating TG by potently inhibiting LPL. We also recently showed that the TG-lowering apolipoprotein A5 (ApoA5) decreases TG levels by suppressing ANGPTL3/8-mediated LPL inhibition.

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Purpose Of Review: Over the last two decades, evolving discoveries around angiopoietin-like (ANGPTL) proteins, particularly ANGPTL3, ANGPTL4, and ANGPTL8, have generated significant interest in understanding their roles in fatty acid (FA) metabolism. Until recently, exactly how this protein family regulates lipoprotein lipase (LPL) in a tissue-specific manner to control FA partitioning has remained elusive. This review summarizes the latest insights into mechanisms by which ANGPTL3/4/8 proteins regulate postprandial FA partitioning.

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Importance: Psoriasis relapse may involve compensatory T-cell activation pathways in the presence of CD28-CD80/CD86 blockade with abatacept.

Objective: To determine whether costimulatory signaling blockade with abatacept prevents psoriasis relapse after ustekinumab withdrawal.

Design, Setting, And Participants: Psoriasis Treatment with Abatacept and Ustekinumab: a Study of Efficacy (PAUSE), a parallel-design, double-blind, placebo-controlled randomized clinical trial, was conducted at 10 sites in the US and Canada.

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We previously demonstrated that angiopoietin-like protein 8 (ANGPTL8) forms ANGPTL3/8 and ANGPTL4/8 complexes that increase with feeding to direct fatty acids (FA) toward adipose tissue through differential modulation of lipoprotein lipase (LPL) activity. Each complex correlated inversely with high density lipoprotein cholesterol (HDL) in control subjects. We thus investigated ANGPTL3/8 and ANGPTL4/8 levels in type 2 diabetes patients, who can present with decreased HDL.

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