Publications by authors named "Renger Witkamp"

Hypothalamic inflammation often coincides with cancer and cachexia-anorexia. Prior work established the significance of tumor-derived inflammatory factors in triggering hypothalamic inflammation, yet the precise mechanisms remained elusive. Here, we demonstrate that prostaglandin E2 (PGE2), produced in the tumor via cyclooxygenase-2 (COX-2), plays a pivotal role in this context.

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Apical-out enteroids mimic the environment well due to their accessible apical surface and mucus layer, making them an ideal model for studying the impact of (bioactive) food compounds. Generated human ileal apical-out enteroids showed a fucose-containing mucus layer surrounding the apical brush border on their exposure side, indicating their physiological relevance. Effects on the mucosal epithelium of antibacterial prenylated phenolics (glabridin, licochalcone A, and glycycoumarin) from licorice roots were investigated for cytotoxicity, cell viability, barrier integrity, and biotransformation.

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Introduction: While observational research suggests a protective role for nutrition in brain aging, intervention studies remain inconclusive. This failing translation from observational to interventional research may result from overlooking nutrient interactions.

Methods: We developed a nutrient status index capturing the number of suboptimal statuses of omega-3 fatty acids, homocysteine, and vitamin D (range 0 to 3).

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Background: The EAT-Lancet commission has proposed a dietary pattern that is both sustainable and healthy. However, the impact of this diet on cognition in older adults remains unexplored. Therefore, we examined the association between adherence to the EAT-Lancet diet and cognitive ageing.

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Beta-glucans and arabinoxylans are known for their immunostimulatory properties. However, in vivo these have been documented almost exclusively following parenteral administration, underemphasizing oral intake. C57BL/6 mice are fed either a control diet or a diet supplemented with yeast-derived whole β-glucan particle (yWGP) or with rice-derived arabinoxylan (rice bran-1) at a concentration of 1%, 2.

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The endocannabinoid system (ECS) is dysregulated during obesity and metabolic disorders. Weight loss favours the re-establishment of ECS homeostatic conditions, but also the fatty acid composition of the diet can modulate endocannabinoid profiles. However, the combined impact of nutrient quality and energy restriction on the ECS remains unclear.

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Background: Interactions between the endocannabinoid system (ECS) and neurotransmitter systems might mediate the risk of developing a schizophrenia spectrum disorder (SSD). Consequently, we investigated in patients with SSD and healthy controls (HC) the relations between (1) plasma concentrations of two prototypical endocannabinoids (N-arachidonoylethanolamine [anandamide] and 2-arachidonoylglycerol [2-AG]) and (2) striatal dopamine synthesis capacity (DSC), and glutamate and y-aminobutyric acid (GABA) levels in the anterior cingulate cortex (ACC). As anandamide and 2-AG might reduce the activity of these neurotransmitters, we hypothesized negative correlations between their plasma levels and the abovementioned neurotransmitters in both groups.

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Arabinoxylans have been identified for a wide range of purported health-promoting applications, primarily attributed to its immunomodulatory effects. Previously, we have reported the ability of arabinoxylans to induce non-specific memory in innate immune cells, commonly referred to as "trained innate immunity". In the present study, we investigated the effect of particle size on innate immune training and resilience in primary human macrophages as well as in a more physiologically relevant macrophage-intestinal epithelial cell co-culture model.

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Article Synopsis
  • A new 3D-apical-out enteroid model for mice was developed to study food-related compounds, enhancing ability to expose the enteroids' apical layer to substances.
  • The apical-out model showed reduced sensitivity to glabridin, with cytotoxicity measurements five times less compared to traditional apical-in models, suggesting a protective mucus layer.
  • This research indicates that certain prenylated phenolic compounds, such as glabridin, do not demonstrate cytotoxic effects in the gastrointestinal tract at their minimum inhibitory concentrations, highlighting their potential for controlling harmful bacteria.
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Aim: To investigate the effects of exercise on salivary concentrations of inflammatory markers by analyzing a panel of 25 inflammatory markers in subjects who had participated in bicycle ergometer tests varying in workload and hydration status.

Methods: Fifteen healthy young men (20-35 years) had performed 4 different exercise protocols of 1 hour duration in a randomly assigned cross-over design, preceded by a rest protocol. Individual workloads depended on participant's pre-assessed individual maximum workload (Wmax): rest (protocol 1), 70% Wmax in hydrated (protocol 2) and dehydrated (protocol 3) state, 50% Wmax (protocol 4) and intermittent 85%/55% Wmax in 2 min blocks (protocol 5).

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Introduction: Studies suggest a role of vitamin D in the progression and symptomatology of Alzheimer's disease (AD), with few in vitro studies pointing to effects on serotonergic and amyloidogenic turnover. However, limited data exist in AD patients on the potential association with cognition and behavioral and psychological signs and symptoms of dementia (BPSD). In this retrospective cross-sectional study, we, therefore, explored potential correlations of serum 25-hydroxyvitamin D3 (25(OH)D3) concentrations, indicative of vitamin D status, with serum serotonin (5-hydroxytryptamine, 5-HT) levels, cognitive/BPSD scorings, and cerebrospinal fluid (CSF) biomarker levels.

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Background: Gamma-aminobutyric acid (GABA) is mainly known as an endogenously produced neurotransmitter. However, GABA intake from dietary sources like tomatoes and fermented foods can be considerable. Studies in rodent models have shown beneficial effects of oral GABA supplementation on glucose homeostasis and cardiovascular health.

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Glucagon-like peptide 1 (GLP-1) is a multifaceted intestinal hormone with diverse physiological functions throughout the body. Previously, we demonstrated that the steviol glycoside rebaudioside A (rebA) from stimulates the release of GLP-1 from mouse intestinal organoids and pig intestinal segments. To further unravel the underlying mechanisms, we examined the involvement of sweet- and bitter taste receptors and their associated signal transduction pathways.

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Purpose: While the benefits of adopting a more plant-based diet for sustainability and animal welfare are clear, its long-term health impacts, including the impact on cognitive ageing, are limited studied. Therefore, we investigated the associations between plant-based diet adherence and cognitive ageing.

Methods: Data from a previous intervention study involving community-dwelling adults aged ≥ 65 years were analysed at baseline (n = 658) and after 2-year follow-up (n = 314).

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Background: Vitamin D deficiency is associated with all-cause dementia and Alzheimer's disease (AD). At the same time, this knowledge is limited specifically for vascular dementia (VaD), while data regarding other subtypes of dementia are even more limited.

Objective: To investigate the association of 25-hydroxy vitamin D (25(OH)D) status with dementia subtypes in an outpatient geriatric population.

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Prenylated phenolics are antimicrobials found in liquorice ( spp.). Liquorice spent is a by-product rich in prenylated phenolics obtained after water extraction of roots, and is currently not valorised.

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Background: Cachexia-anorexia syndrome is a complex metabolic condition characterized by skeletal muscle wasting, reduced food intake and prominent involvement of systemic and central inflammation. Here, the gut barrier function was investigated in pancreatic cancer-induced cachexia mouse models by relating intestinal permeability to the degree of cachexia. We further investigated the involvement of the gut-brain axis and the crosstalk between tumour, gut and hypothalamus in vitro.

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The adequate quantification of endocannabinoids and related N-acylethanolamines can be complex due to their low endogenous levels, structural diversity, and metabolism. Therefore, advanced analytical approaches, involving LC-MS, are required to quantify these molecules in plasma, tissues, and other matrices. It has been shown that endocannabinoid congeners synthesized from n-3 poly-unsaturated fatty acids (n-3 PUFAs), such as docosahexaenoylethanolamide (DHEA) and eicosapentaenoylethanolamide (EPEA), have interesting immunomodulatory and tumor-inhibiting properties.

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We studied the mechanistic and biological origins of anti-inflammatory poly-unsaturated fatty acid-derived -acylethanolamines using synthetic bifunctional chemical probes of docosahexaenoyl ethanolamide (DHEA) and arachidonoyl ethanolamide (AEA) in RAW264.7 macrophages stimulated with 1.0 μg mL lipopolysaccharide.

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Gamma-aminobutyric acid (GABA) and its precursor glutamate play signaling roles in a range of tissues. Both function as neurotransmitters in the central nervous system, but they also modulate pancreatic and immune functioning, for example. Besides endogenous production, both compounds are found in food products, reaching relatively high levels in tomatoes.

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Purpose: Trials aiming to lower homocysteine by B-vitamin supplementation have reported mixed results on slowing cognitive decline. We investigated if efficacy of B-vitamin supplementation is affected by baseline plasma omega-3 fatty acid levels.

Methods: This post-hoc analysis of the B-proof trial included 191 adults aged 65 years or older with baseline plasma total homocysteine ≥ 12 μmol/L, randomly assigned to 400 µg folic acid and 500 µg vitamin B12 or placebo daily for 2 years.

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Arabinoxylans of various structures and sources have shown to possess the ability to induce a range of immune responses in different cell types in vitro and in vivo. Although the underlying mechanisms remain to be fully established, several studies point towards the involvement of activation of pattern recognition receptors (PRRs). Activation of specific PRRs (i.

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Traditional foods and diets can provide health benefits beyond their nutrient composition because of the presence of bioactive compounds. In various traditional healthcare systems, diet-based approaches have always played an important role, which has often survived until today. Therefore, investigating traditional foods aimed at health promotion could render not only novel bioactive substances but also mechanistic insights.

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Background: Pulmonary hypertension (PH) is a rare progressive and lethal disease affecting pulmonary arteries and heart function. The disease may compromise the nutritional status of the patient, which impairs their physical performance. This study aimed to determine the prevalence of micronutrient deficiencies in pulmonary arterial hypertension (PAH) and chronic thrombo-embolic pulmonary hypertension (CTEPH) patients.

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Targeted exercise combined with nutritional and pharmacological strategies is commonly considered to be the most optimal strategy to reduce the development and progression of cachexia. For COPD patients, this multi-targeted treatment has shown beneficial effects. However, in many, physical activity is seriously hampered by frailty and fatigue.

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