Publications by authors named "Erik Mulder"

Conventional vaccines rarely cause severe allergic reactions. However, the rapid development and approval of COVID-19 vaccines left limited initial data on their adverse reactions, particularly in individuals with a history of allergy. The aim of this study was to assess and compare the safety profile of different doses and brands of COVID-19 vaccines in subjects with a history of allergy vs.

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Article Synopsis
  • The study investigates the safety of COVID-19 vaccines in immunocompromised patients by comparing their reported adverse drug reactions (ADRs) to a control group.
  • It involved a cohort of immunocompromised individuals from 11 European countries who completed electronic questionnaires to track ADRs after vaccination between February 2021 and February 2023.
  • Results show that immunocompromised participants reported higher rates of common ADRs, like injection-site pain and fatigue, compared to their matched non-immunocompromised counterparts, particularly after the first vaccine dose.
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Article Synopsis
  • The study examines adverse drug reactions (ADRs) reported by individuals who received COVID-19 vaccinations, comparing those with a history of SARS-CoV-2 infection to those without, across different vaccine brands and doses.
  • Conducted from February 2021 to February 2023, it included 4,788 vaccinees and found that those with previous infections reported higher ADRs after the first and booster doses, but lower ADRs after the second dose.
  • Overall, while the frequency of serious ADRs was low, the study highlights the variation in reported reactions based on prior infection history and the type and timing of vaccine doses.
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Introduction: During the COVID-19 pandemic, EMA set-up a large-scale cohort event monitoring (CEM) system to estimate incidence rates of patient-reported adverse drug reactions (ADRs) of different COVID-19 vaccines across the participating countries. This study aims to give an up to date and in-depth analysis of the frequency of patient-reported ADRs after the 1st, 2nd, and booster vaccination, to identify potential predictors in developing ADRs and to describe time-to-onset (TTO) and time-to-recovery (TTR) of ADRs.

Methods: A CEM study was rolled out in a period ranging from February 2021 to February 2023 across multiple European countries; The Netherlands, Belgium, France, the United Kingdom, Italy, Portugal, Romania, Slovakia and Spain.

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With Latent Class Analysis applied on data of 98 children with autism spectrum disorder (ASD) (9-12 years; 17 girls) participating in social skills training (SST) in a randomized controlled trial (Dekker et al. 2019), four subgroups were detected, based on social-communicative skills before, and response patterns to training. Two subgroups improved after SST.

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In 122 high-functioning children with autism spectrum disorder (ASD; 9-13 years; 19 girls), we investigated the effectiveness of a 15-session social skills group training (SST) with and without parent and teacher involvement (PTI) in a randomized controlled trial with three conditions: SST (n = 47), SST-PTI (n = 51), and care-as-usual (CAU, n = 24). Hierarchical linear modeling was used for immediate and 6-month follow-up analyses. Measures were administered before randomization (blind), post-treatment and at follow-up (not blind).

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The Social skills Observation Measure (SOM) is a direct observation method for social skills used in naturalistic everyday situations in school. This study describes the development of the SOM and investigates its psychometric properties in 86 children with Autism spectrum disorder, aged 9.8-13.

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Background: Social skills training (SST) is a common intervention for children with autism spectrum disorders (ASDs) to improve their social and communication skills. Despite the fact that SSTs are often applied in clinical practice, the evidence for the effectiveness of these trainings for children with ASD is inconclusive. Moreover, long term outcome and generalization of learned skills are little evaluated.

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The rooting reflex has long been studied by neurologists and developmentalists and is defined as an orientation toward tactile stimulation in the perioral region or visual stimulation near the face. Nearly, all previous reports of the visual rooting reflex (VRR) concern its presence in adults with neurological dysfunction. Previously, the VRR was reported to be present in a majority of individuals with autism and absent in control subjects.

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Weight gain is an important adverse effect of risperidone, but predictors of significant weight gain have yet to be identified in pediatric patients. Here, we investigated differences between age- and gender-normed body mass index-standardized z scores at baseline and after 8 weeks of open-label, flexible-dose risperidone treatment (mean dose: 1.70  mg/day) in 32 youths with pervasive developmental disorder (mean age = 8.

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Background: Autism spectrum disorders (ASDs) are a group of highly heritable neurodevelopmental disorders which are characteristically comprised of impairments in social interaction, communication and restricted interests/behaviours. Several cell adhesion transmembrane leucine-rich repeat (LRR) proteins are highly expressed in the nervous system and are thought to be key regulators of its development. Here we present an association study analysing the roles of four promising candidate genes - LRRTM1 (2p), LRRTM3 (10q), LRRN1 (3p) and LRRN3 (7q) - in order to identify common genetic risk factors underlying ASDs.

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Over the past decade, research on the genetic variants underlying susceptibility to autism and autism spectrum disorders (ASDs) has focused on linkage and candidate gene studies. This research has implicated various chromosomal loci and genes. Candidate gene studies have proven to be particularly intractable, with many studies failing to replicate previously reported associations.

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Objective: A substantial proportion of individuals with autism have elevated levels of platelet serotonin (5-HT). We examined whether platelet hyperserotonemia is associated with increased gut 5-HT synthesis, altered 5-HT catabolism or altered melatonin production.

Methods: Urinary excretion of 5-hydroxyindoleacetic acid (5-HIAA) and 5-HT was compared in 10 normoserotonemic and 10 hyperserotonemic age-matched autistic individuals.

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The Children's Social Behavior Questionnaire (CSBQ) was compared with the Autism Diagnostic Interview-Revised (ADI-R), Autism Diagnostic Observation Schedule (ADOS), and clinical classification in children with mild and moderate intellectual disability (ID), to investigate its criterion related validity. The contribution of the CSBQ to a classification of Autism Spectrum Disorder (ASD) was most specific for the subscales 'contact' and 'stereotyped', with high coherence with all three classification methods. The CSBQ may be used as a signaling, screening, or describing instrument for children with ASD and ID, as it complements other methods by adding unique information about the clinical presentation.

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Objective: Autistic spectrum disorders are childhood neurodevelopmental disorders characterized by social and communicative impairment and repetitive and stereotypical behavior. Macrophage migration inhibitory factor (MIF) is an upstream regulator of innate immunity that promotes monocyte/macrophage-activation responses by increasing the expression of Toll-like receptors and inhibiting activation-induced apoptosis. On the basis of results of previous genetic linkage studies and reported altered innate immune response in autism spectrum disorder, we hypothesized that MIF could represent a candidate gene for autism spectrum disorder or its diagnostic components.

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Objective: This study investigated the interrelationship between psychopharmacotherapy in general and the use of specific psychotropic drugs and pervasive developmental disorder and other behavior problems in children and adolescents with mental retardation.

Methods: A total of 862 participants 4 to 18 years of age, including all levels of mental retardation, were recruited through facilities for children with mental retardation in Friesland, The Netherlands. Information on medication was collected through parent interviews.

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Background: Quantification of 5-hydroxyindole-3-acetic acid (5-HIAA) in urine is useful in diagnosing and monitoring of patients with carcinoid tumors and in the study of serotonin (5-hydroxytryptamine) metabolism in various disorders. We describe an automated method that incorporates on-line solid-phase extraction (SPE) and HPLC to measure urinary 5-HIAA.

Methods: Automated prepurification of urine was accomplished with HySphere-resin GP SPE cartridges containing strong hydrophobic polystyrene resin.

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Two putatively functional polymorphisms of the serotonin transporter gene (HTT, SLC6A4) were examined for associations with risk for pervasive developmental disorders (PDDs) and specific autism phenotypes. Dutch patients diagnosed with PDD (N = 125, age range 5-20 years, DSM-IV-TR based criteria, ADI-R and ADOS behavioral assessments) and their parents (N = 230) were genotyped for promoter ins/del (5-HTTLPR) and intron 2 variable number of tandem repeats (VNTR) alleles. Using the transmission disequilibrium test (TDT), no disorder-specific preferential transmission of promoter (long and short) or intron 2 (10- and 12-repeat) alleles was observed.

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Background: The Children's Communication Checklist (CCC; Bishop, 1998) is a questionnaire that was developed to measure pragmatic language use and may be completed by parents and teachers. Two studies are reported, which were designed to investigate: (1) whether children with Attention Deficit Hyperactivity Disorder (ADHD) encounter pragmatic language problems in comparison with normal controls (NC), (2) whether children with ADHD and children with High Functioning Autism (HFA) can be differentiated using the CCC, (3) the usefulness of the CCC for parents and teachers in a clinical and in a research setting, and (4) the role of age in pragmatic language use in ADHD and HFA.

Method: In the first study (clinical sample) 50 children with ADHD, 50 children with HFA, and 50 NC were compared to each other using the CCC.

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Objective: To investigate group differences, the within-group distributions, and the clinical correlates of platelet serotonin (5-HT) levels in pervasive developmental disorders (PDD).

Method: Platelet 5-HT levels were measured in Dutch children and young adults, recruited from 2001 through 2003, with PDD (autism, Asperger's, and PDD-not otherwise specified [PDD-NOS]; n = 81) or with mental retardation (MR; n = 54) but without PDD, and in normal controls (n = 60). The distribution of platelet 5-HT levels was assessed using mixture-modeling analyses.

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The interrelationship between the Autism Diagnostic Interview-Revised (ADI-R), Autism Diagnostic Observation Schedule-Generic (ADOS-G) and clinical classification was studied in 184 children and adolescents with Mental Retardation (MR). The agreement between the ADI-R and ADOS-G was fair, with a substantial difference between younger and older children (5-8 vs. 8+ years).

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