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Biomedical subjects

Peter Paul De Deyn

Publications and source records attributed to Peter Paul De Deyn.

At least 19 recordsLinked to original sources

Intraneuronal amyloid beta and reduced brain volume in a novel APP T714I mouse model for Alzheimer's disease.

Transgenic mouse models of Alzheimer's disease (AD) expressing high levels of amyloid precursor protein (APP) with familial AD (FAD) mutations have proven to be extremely useful in understanding pathogenic processes of AD especially those that involve amyloidogenesis. We earlier described Austrian APP T714I pathology that leads to one of the earliest AD age-at-onsets with abundant intracellular and extracellular amyloid deposits in brain. The latter strikingly was non-fibrillar diffuse amyloid, composed of N-truncated A beta 42 in absence of A beta 40. In vitro, this mutation leads to one of the highest A beta 42/A beta 40 ratios among all FAD mutations. We generated an APP T714I transgenic mouse model that despite having 10 times lower transgene than endogenous murine APP deposited intraneuronal A beta in brain by 6 months of age. Accumulations increased with age, and this was paralleled by decreased brain sizes on volumetric MRI, compared to age-matched and similar transgene-expressing APP wild-type mice, although, with these levels of transgenic expression we did not detect neuronal loss or significant memory impairment. Immunohistochemical studies revealed that the majority of the intraneuronal A beta deposits colocalized with late endosomal markers, although some A beta inclusions were also positive for lysosomal and Golgi markers. These data support earlier observations of A beta accumulation in the endosomal-lysosomal pathway and the hypothesis that intraneuronal accumulation of A beta could be an important factor in the AD pathogenesis.

Alzheimer Disease↗

APP23 mice display working memory impairment in the plus-shaped water maze.

Alzheimer's disease (AD) patients typically present short-term memory deficits, before long-term memory capacity declines with disease progression. Several studies have described learning and memory deficits in the APP23 mouse model. Our group reported a decline of learning and memory capacities from the age of 3 months onwards using a hidden-platform Morris water maze (MWM). The aim of the present study was to evaluate working and reference memory in APP23 mice in the same plus-shaped water maze. The transgenic mice had slower learning curves; however, consolidation of the learned information appeared intact in this learning paradigm. This report demonstrates impairment of working memory in this transgenic Alzheimer model.

Amyloid beta-Protein Precursor↗

Treating behavioral and psychological symptoms in patients with psychosis of Alzheimer's disease using risperidone.

OBJECTIVES: To examine the effect of risperidone on specific behavioral and psychological symptoms of dementia (BPSD) among patients with psychosis of Alzheimer's disease (AD). METHODS: Post hoc exploratory analysis of data on 479 nursing-home patients with psychosis of AD from three 12-week, double-blind, placebo-controlled clinical trials. Criteria for psychosis of AD were a diagnosis of AD or mixed dementia and a rating of >/= 2 on any delusion or hallucination item of the Behavioral Pathology in Alzheimer's Disease (BEHAVE-AD) rating scale when entering the trial. Mean changes from baseline to endpoint were examined for items on the Cohen-Mansfield Agitation Inventory (CMAI) and BEHAVE- AD. RESULTS: On the CMAI, risperidone was significantly more effective than placebo in treating cursing or verbal aggression (p = 0.004), hitting (p < 0.001), performing repetitious mannerisms (p < 0.001), pacing, aimless wandering (p = 0.017), hoarding things (p = 0.02), hiding things (p = 0.02) and repetitive sentences or questions (p = 0.025). On the BEHAVE-AD, risperidone was significantly more effective than placebo in treating physical threats and/or violence (p = 0.001), agitation (other) (p = 0.001) and verbal outbursts (p = 0.026). Although analysis on individual hallucination and delusional items did not demonstrate specific responses, analyses of a composite of delusional items revealed significant drug-placebo differences. CONCLUSIONS: These data indicate that risperidone is effective in treating a variety of symptoms associated with psychosis of AD.

Aged↗

Risperidone in the management of agitation and aggression associated with psychiatric disorders.

OBJECTIVE: This review provides an overview of the prevalence and treatment of agitation and aggression, and focuses on the use of risperidone to treat these symptoms in patients from different age groups. METHODS: MEDLINE and EMBASE databases were used to identify controlled studies of risperidone in the treatment of disruptive behavior disorders and pervasive developmental disorders in pediatric patients, acute agitation or aggression in adults, and psychological and behavioral symptoms of dementia in the elderly. Additionally, key open-label, long-term trials assessing the efficacy and safety of risperidone were considered. RESULTS: The results of the 19 double-blind studies identified showed that risperidone is effective in treating agitation and aggression in the different populations, regardless of age. The safety and tolerability of risperidone appear to be good overall but certain safety issues, such as a higher risk of cerebrovascular adverse events in the elderly with dementia, were highlighted. CONCLUSIONS: Risperidone is useful for treating aggression and agitation associated with various psychiatric disorders in patients from different age groups.

Aggression↗

Actigraphic measurement of agitated behaviour in dementia.

OBJECTIVES: This study examines the correlation between actigraphic measures and a validated assessment scale of agitated behaviour in dementia, the Cohen-Mansfield Agitation Inventory (CMAI). METHODS: A total of 110 patients were included. Patients either suffered from Alzheimer dementia (AD), mixed dementia (MXD), frontotemporal dementia (FTD) or diffuse Lewy body disease (DLB). All patients underwent actigraphic recordings for 48 h. CMAI was scored by professional caretakers, who were responsible for the patient during his or her actigraphic recording. RESULTS: Patients with high total CMAI scores (>or= 50) clearly had higher levels of activity during the day as measured by means of actigraphy than patients with low total CMAI scores (ANOVA, F=126.75, p<0.0001). Patients with low MMSE scores (<20) also had higher activity levels during the day than patients with higher MMSE scores (ANOVA, F= 85.74, p<0.0001). Correlations between ctigraphic data and CMAI total scores were moderate but highly significant. CONCLUSION: We conclude that actigraphy is a useful tool to examine agitated behaviour in dementia.

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Effects of rivastigmine in patients with and without visual hallucinations in dementia associated with Parkinson's disease.

We aimed to determine prospectively whether rivastigmine, an inhibitor of acetylcholinesterase and butyrylcholinesterase, provided benefits in patients with and without visual hallucinations in a population with dementia associated with Parkinson's disease (PDD). This was a 24-week double-blind placebo-controlled study. Primary efficacy measures were the Alzheimer's Disease Assessment Scale cognitive subscale (ADAS-cog) and Alzheimer's Disease Cooperative Study-Clinician's Global Impression of Change (ADCS-CGIC). Secondary efficacy measures included activities of daily living, behavioral symptoms, and executive and attentional functions. Patients were stratified according to the presence of visual hallucinations at baseline. The study included 188 visual hallucinators (118 on rivastigmine, 70 on placebo) and 348 nonvisual hallucinators (239 on rivastigmine, 109 on placebo). Rivastigmine provided benefits in both visual hallucinators and nonvisual hallucinators. Absolute responses to rivastigmine on the ADAS-cog were comparable over 6 months, although rivastigmine-placebo differences tended to be larger in visual hallucinators (4.27; P = 0.002) than in nonhallucinators (2.09; P = 0.015). On the ADCS-CGIC, differences between rivastigmine and placebo were 0.5 in visual hallucinators (P = 0.030) and 0.3 in nonhallucinators (P = 0.111). Rivastigmine provided benefits on all secondary efficacy measures, and placebo declines and treatment differences were more marked in visual hallucinators. Adverse events were reported more frequently by rivastigmine-treated patients, although this difference was less marked in visual hallucinators. Visual hallucinations appear to predict more rapid decline and possibly greater therapeutic benefit from rivastigmine treatment in PDD.

Aged↗

Aggressive male APP23 mice modeling behavioral alterations in dementia.

In addition to cognitive deterioration, Alzheimer's disease patients exhibit behavioral and psychological signs and symptoms of dementia. Behavioral alterations are a major source of caregiver stress and an important contributor in the decision to institutionalize patients. The amyloid precursor protein (APP) 23 transgenic mouse model develops amyloid plaques from the age of 6 months onward and exhibits tau pathology, which is absent in most other amyloid-based models. Besides mimicking the demented patients' memory deficits, these transgenic mice present with various behavioral disturbances, thereby approximating the clinical situation remarkably well. Using an isolation-induced/resident-intruder paradigm of aggression, the authors revealed increased aggressiveness in male APP23 mice at the ages of 6 and 12 months. The presence of aggressive disturbances in this valuable mouse model opens perspectives to evaluate aggression-modulating therapies.

Age Factors↗

Drug discovery in dementia: the role of rodent models.

Recent advances in the understanding of the pathophysiological mechanisms underlying Alzheimer's disease have pointed to novel strategies for drug development. Animal models have contributed considerably to these advances, and will have a key role in the evaluation of therapeutics that could have the potential not just to alleviate the dementia associated with Alzheimer's disease, but to modify the disease process. Here, we summarize and critically evaluate current rodent models of dementia, and discuss their role in drug discovery and development.

Alzheimer Disease↗

Relationship between outcome and baseline blood pressure and other haemodynamic measures in acute ischaemic stroke: data from the TAIST trial.

BACKGROUND: A poor outcome after stroke is associated independently with high blood pressure during the acute phase; however, relationships with other haemodynamic measures [heart rate (HR), pulse pressure (PP), rate-pressure product (RPP)] remain less clear. METHODS: The Tinzaparin in Acute Ischaemic Stroke Trial is a randomised, controlled trial assessing the safety and efficacy of tinzaparin versus aspirin in 1484 patients with acute ischaemic stroke. Systolic blood pressure (SBP), diastolic blood pressure (DBP) and HR measurements taken immediately prior to randomization were averaged, and the mid-blood pressure (MBP), PP, mean arterial pressure (MAP), pulse pressure index, and RPP were calculated. The relationship between these haemodynamic measures and functional outcome (death or dependency, modified Rankin Scale > 2) and early recurrent stroke, were studied with adjustment for baseline prognostic factors and treatment group. Odds ratios (OR) and 95% confidence intervals (CI) refer to a change in haemodynamic measure by 10 points. RESULTS: A poor functional outcome was associated with SBP (adjusted OR; 1.11; 95% CI, 1.03-1.21), HR (adjusted OR; 1.15; 95% CI, 1.00-1.31), MBP (adjusted OR; 1.15, 95% CI, 1.03-1.29), PP (adjusted OR; 1.14; 95% CI, 1.02-1.26), MAP (adjusted OR; 1.15; 95% CI, 1.02-1.31) and RPP (adjusted OR; 1.01; 95% CI, 1.00-1.02). Early recurrent stroke was associated with SBP, DBP, MBP and MAP. CONCLUSIONS: A poor outcome is independently associated with elevations in blood pressure, HR and their derived haemodynamic variables, including PP and the RPP. Agents that modify these measures may improve functional outcome after stroke.

Aged↗

Small cell lung carcinoma presenting as collapsin response-mediating protein (CRMP) -5 paraneoplastic optic neuropathy.

A 77-year-old woman presenting with progressive visual loss in both eyes was found to have small cell lung cancer. Assay for collapsin response-mediating protein (CRMP) -5 was positive suggesting a paraneoplastic optic neuropathy (PON). During treatment of the small cell lung cancer, the patient died of pneumonia and autopsy disclosed neuropathologic abnormalities consistent with PON. This is only the second case of CRMP-5-confirmed PON to report neuropathologic findings.

Aged↗

Intracerebral adeno-associated virus-mediated gene transfer in rapidly progressive forms of metachromatic leukodystrophy.

Metachromatic leukodystrophy (MLD) is a neurodegenerative lysosomal disease caused by a defect of the enzyme arylsulfatase A (ARSA) that disrupts the degradation of sulfatides (Sulf) in neurons and glial cells. Therapy for MLD requires active production of ARSA in the brain to prevent demyelination and neuronal damage, and efficient delivery of ARSA to act faster than disease progression, particularly in the rapidly progressive late infantile form. We used an adeno-associated virus serotype 5 (AAV5) vector to express the human ARSA gene in the brain of MLD mouse model. We achieved rapid, extensive and long-lasting expression of the recombinant ARSA in the brain, cerebellum and brainstem from at least 3 to 15 months post-injection. Analysis of the vector genome and ARSA distribution gave evidence for in vivo cross-correction of many untransduced neurons and astrocytes. ARSA delivery rapidly reversed Sulf storage and prevented neuropathological abnormalities and neuromotor impairment. We believe that AAV5-mediated brain delivery of ARSA is a potentially efficacious therapeutic strategy for MLD patients, especially for those with rapidly progressive form of the disease.

Adenoviridae↗

Effect of Morris water maze diameter on visual-spatial learning in different mouse strains.

The Morris water maze task is a widely used tool to assess hippocampus-dependent learning and memory in rodents. Performance depends upon several factors including not only the traits of the experimental animals, but also apparatus and protocol characteristics. The present study aimed at investigating the effect of maze diameter on acquisition and probe trial performance in three commonly used strains: C57Bl/6, BALB/c, and 129/SvEvBrd mice. Three maze diameters (150, 120, and 75 cm) were used under identical protocol and testing conditions. Downscaling maze dimensions, hence reducing difficulty and stress levels, did not allow BALB/c mice, commonly known as poor learners, to acquire this visual-spatial learning task. C57Bl/6 mice performed satisfactory in all three maze settings, with superior probe trial performance in the 120-cm-diameter setting. Further downscaling of maze dimensions might even render this task too simple for this strain. If the 129S5/SvEvBrd background strain is preferred, testing of visual-spatial learning abilities should be performed in a small sized MWM pool, as this strain performed only adequately in the smallest maze setting. Attention is drawn to the importance of supplying a detailed description 129 substrain nomenclature in future studies. Generalization of observations from one strain to another and from data obtained with a specific strain and maze diameter to other maze dimensions should be dealt with very carefully. The present study emphasizes the importance of a well-substantiated choice of background strain and water maze characteristics when researchers plan to investigate visual-spatial learning and memory in a chemically/lesion-induced or targeted mutagenesis model.

Animals↗

The UBQLN1 polymorphism, UBQ-8i, at 9q22 is not associated with Alzheimer's disease with onset before 70 years.

An intronic polymorphism affecting alternative splicing of exon 8 of ubiquilin 1 (UBQLN1), that is located at a well established Alzheimer's disease (AD) locus on chromosome 9q22, was recently associated with increased risk for late-onset AD. We analyzed this polymorphism in two independent AD samples consisting of patients with an onset age 70 years or less, but did not observe statistically significant association. Our study does not support a major role for this UBQLN1 polymorphism in AD patients with an earlier onset of disease.

Adaptor Proteins, Signal Transducing↗

Cognitive evaluation of disease-modifying efficacy of galantamine and memantine in the APP23 model.

With increasing knowledge of molecular, biochemical and cellular events causing synaptic dysfunction and neurodegeneration in Alzheimer-diseased brain, preventive treatment strategies are emerging. Neuroprotective capacities have been attributed to galantamine and memantine. The age-dependent cognitive decline in the APP23 model was employed to evaluate disease-modifying efficacy of chronic treatment with both compounds. At age 6 weeks, heterozygous APP23 mice were subcutaneously implanted with osmotic pumps delivering saline, galantamine (1.3 or 2.6 mg/kg/day) or memantine (7.2 or 14.4 mg/kg/day). After 2 months of treatment, a 3-week wash-out period was allowed to prevent bias from sustained symptomatic effects. Subsequently, cognitive evaluation in the Morris water maze commenced. Galantamine low dose significantly improved spatial accuracy during probe trial. Memantine improved acquisition performance (path length) and spatial accuracy during probe trial in a dose-dependent manner. This is the first study reporting disease-modifying efficacy of galantamine and memantine in transgenic mice modeling Alzheimer's disease.

Alzheimer Disease↗

Cognitive decline, neuromotor and behavioural disturbances in a mouse model for fragile-X-associated tremor/ataxia syndrome (FXTAS).

Carriers of premutation alleles (55-200 CGG repeats) of the fragile X mental retardation 1 (FMR1) gene are spared the major neurodevelopmental symptomatology of fragile X syndrome patients carrying a full mutation (>200 repeats). In a proportion of premutation carriers, the repeat expansion is associated with a specific neurological profile involving intention tremor, ataxia, intellectual decline compatible with dementia syndrome, Parkinsonism and autonomic dysfunction at older age, commonly referred to as fragile-X-associated tremor/ataxia syndrome (FXTAS). Typical CNS changes include hyperintense signals on T2 weighted magnetic resonance images and the presence of ubiquitin-positive intranuclear neuronal inclusions. A knock-in mouse model with a (CGG)98 repeat in the premutation range has been generated and shown to exhibit elevated Fmr1 mRNA levels and ubiquitin-positive intranuclear neuronal inclusions, suggesting it may be a valid model for the human disease. Given the specific clinical profile of FXTAS patients, the expanded CGG repeat model was assessed for cognitive, behavioural and neuromotor performance at different ages (20, 52 and 72 weeks). The Morris water maze task exposed age-dependent decline of visual-spatial memory. Open field recordings revealed decreased exploration of the centre of the arena in the oldest group of expanded CGG repeat mice, potentially reflecting increased anxiety. Neuromotor tasks primarily showed decline of performance on the accelerating rotarod with age in the premutation carriers but not in control littermates. The age-dependent cognitive decline and neuromotor disturbances may be related to the progressive cognitive and behavioural difficulties observed in FXTAS patients.

Age Factors↗

Biochemical and behavioural phenotyping of a mouse model for GAMT deficiency.

Deficiency of guanidinoacetate N-methyltransferase (GAMT) is the first described creatine (CT) deficiency syndrome in man, biochemically characterized by accumulation of guanidinoacetic acid (GAA) and depletion of CT. Patients exhibit severe developmental and muscular problems. We created a mouse model for GAMT deficiency, which exerts biochemical changes comparable with those found in human GAMT-deficient subjects. CT and creatinine (CTN) levels are significantly decreased and GAA is increased in knockout (KO) mice. In patients, other guanidino compounds (GCs) appear to be altered as well, which may also contribute to the symptomatology. Extensive evaluation of GCs levels in the GAMT mouse model was therefore considered appropriate. Concentrations of 13 GCs in plasma, 24-h urine, brain and muscle of GAMT mice were measured. We also report on the detailed behavioural characterization of this model for GAMT deficiency. Besides an increase of GAA and a decrease of CT and CTN in plasma, 24-h urine, brain and muscle of KO mice, we observed a significant increase of other GCs in brain and muscle that was sometimes reflected in plasma and/or urine. KO mice displayed mild cognitive impairment. In general, it could be concluded that the GAMT mouse model is very useful for biochemical research of GAMT deficiency, but shows only a mild cognitive deficit.

Animals↗

Grouping for behavioral and psychological symptoms in dementia: clinical and biological aspects. Consensus paper of the European Alzheimer disease consortium.

Behavioral and psychological symptoms of dementia (BPSD), constitute a major clinical component of Alzheimer's disease (AD). There is a growing interest in BPSD as they are responsible for a large share of the suffering of patients and caregivers, and they strongly determine the patient's lifestyle and management. Better detection and understanding of these symptoms is essential to provide appropriate management. This article is a consensus produced by the behavioral group of the European Alzheimer's Disease Consortium (EADC). The aim of this article is to present clinical description and biological correlates of the major behavioral and psychological symptomatology in AD. BPSD is not a unitary concept. Instead, it should be divided into several symptoms or more likely: groups of symptoms, each possibly reflecting a different prevalence, course over time, biological correlate and psychosocial determinants. There is some clinical evidence for clusters within groups of BPSD. Biological studies indicate that patients with AD and BPSD are associated with variations in the pathological features (atrophy, brain perfusion/metabolism, histopathology) when compared to people with AD without BPSD. An individually tailored approach taking all these aspects into account is warranted as it may offer more, and better, pharmacological and non-pharmacological treatment opportunities.

Aged↗