Identification of novel and recurrent glucokinase mutations in Belgian and Luxembourg maturity onset diabetes of the young patients [1]

in Clinical Genetics (2006), 70(4), 355-359

[No abstract available]

Identification of the underlying mechanism of the c.192G>C mutation in the DJ-1 gene and functional characterisation in patient-based cellular models of Parkinson’s disease ex vivo

Doctoral thesis (2015)

Parkinson’s disease (PD) is the second most common neurodegenerative disease and characterised by a progressive loss of dopaminergic neurons in the substantia nigra pars compacta and in other brain ... [more ▼]

Parkinson’s disease (PD) is the second most common neurodegenerative disease and characterised by a progressive loss of dopaminergic neurons in the substantia nigra pars compacta and in other brain regions. Homozygous loss-of-function mutations in the DJ-1 gene (PARK7) are a rare cause of familial early-onset PD. The protein encoded by PARK7 is involved in a variety of biological processes including transcriptional regulation, chaperone-like functions, oxidative stress response and mitochondrial protection. In the present study, we deciphered novel molecular mechanisms underlying the pathogenicity of the c.192G>C DJ-1 mutation previously predicted to lead to a p.E64D amino acid exchange in the DJ-1 protein. To analyse the c.192G>C DJ-1 mutation, we generated and characterised different ex vivo patient-based cellular models including patient-derived primary fibroblasts, immortalised fibroblasts, induced pluripotent stem cells (iPSCs), iPSC-derived small molecule neuronal precursor cells (smNPCs) as well as iPSC-derived midbrain-specific dopaminergic (mDA) neurons. Analyses of DJ-1 expression in these patient-derived model systems from homozygous carriers of the c.192G>C DJ-1 mutation unexpectedly revealed that this mutation leads to the loss of DJ-1 protein in these cell types. Further experiments using qPCR and an in vitro splicing assay showed a splicing defect causing complete skipping of the mutation-carrying exon 3 in the pre-mRNA. After deciphering the pathogenic mechanism, we developed a targeted genetic rescue strategy of the pathological skipping of exon 3. This was performed by using a specific U1 snRNA that specifically binds to the mutated DJ-1 pre-mRNA and allows for the re-induction of physiological splicing. In addition, we extended our strategy by first candidate approaches aiming at a pharmacological rescue that may offer novel causative treatment options in patients carrying the c.192G>C DJ-1 mutation as well as for other diseases caused by the same mutational mechanism. Beyond the molecular genetic characterisation, we developed different patient-based cellular models and addressed the functional effects of loss of DJ-1 protein in different patient-derived cells carrying the c.192G>C DJ-1 mutation (human fibroblasts, iPSC-derived mDA neurons). These analyses revealed mitochondrial impairments upon loss of DJ-1 protein in fibroblasts, including fragmentation and reduced branching of mitochondria as well as a reduced mitochondrial membrane potential compared to healthy controls. The results correlate with our observations in primary cells from DJ-1 knockout mice and support the idea of a conserved role of DJ-1 in maintaining mitochondrial function. Moreover, mDA neurons of the index patient carrying the homozygous c.192G>C DJ-1 mutation showed in-creased lesion rates of mtDNA and no increase in mtDNA copy numbers, suggesting a lack of compensatory capacity. Our data substantially contribute to the understanding of mechanisms and functions of DJ-1 mutations in PD pathogenesis, in particular focusing on mitochondrial phenotypes upon loss of DJ-1 in different human ex vivo models. This underlines the role of DJ-1 as an important key player in the response to oxidative stress and the maintenance of proper mitochondrial function and homeostasis. Overall, we show that the fibroblasts with an inherited c.192G>C DJ-1 mutation, mDA neurons differentiated from iPSCs of these human fibroblasts and the DJ-1 knockout mice constitute excellent knockout model systems to further dissect the role of DJ-1 in neurodegeneration in PD. This also offers human DJ-1 knockout models for future iso-genic control experiments with a restituted endogenous DJ-1 background. Sequentially, it is possible to test whether disease related phenotypes might be rescued by reintroducing DJ-1 or correcting the defective splicing. Finally, the discovery of the underlying mechanism of the c.192G>C DJ-1 mutation opens up novel opportunities for a first genetic and maybe even pharmacological causative treatment for PD. [less ▲]

Identifying potential survival strategies of HIV-1 through virus-host protein interaction networks

in BMC Systems Biology (2010), 15

Background: The National Institute of Allergy and Infectious Diseases has launched the HIV-1 Human Protein Interaction Database in an effort to catalogue all published interactions between HIV-1 and human ... [more ▼]

Background: The National Institute of Allergy and Infectious Diseases has launched the HIV-1 Human Protein Interaction Database in an effort to catalogue all published interactions between HIV-1 and human proteins. In order to systematically investigate these interactions functionally and dynamically, we have constructed an HIV-1 human protein interaction network. This network was analyzed for important proteins and processes that are specific for the HIV life-cycle. In order to expose viral strategies, network motif analysis was carried out showing reoccurring patterns in virus-host dynamics. RESULTS: Our analyses show that human proteins interacting with HIV form a densely connected and central sub-network within the total human protein interaction network. The evaluation of this sub-network for connectivity and centrality resulted in a set of proteins essential for the HIV life-cycle. Remarkably, we were able to associate proteins involved in RNA polymerase II transcription with hubs and proteasome formation with bottlenecks. Inferred network motifs show significant over-representation of positive and negative feedback patterns between virus and host. Strikingly, such patterns have never been reported in combined virus-host systems. CONCLUSIONS: HIV infection results in a reprioritization of cellular processes reflected by an increase in the relative importance of transcriptional machinery and proteasome formation. We conclude that during the evolution of HIV, some patterns of interaction have been selected for resulting in a system where virus proteins preferably interact with central human proteins for direct control and with proteasomal proteins for indirect control over the cellular processes. Finally, the patterns described by network motifs illustrate how virus and host interact with one another. [less ▲]

Impact of continuous glucose monitoring on quality of life, treatment satisfaction, and use of medical care resources: analyses from the SWITCH study

in Acta Diabetologica (2014), 51(5), 845-851

To investigate the impact of continuous glucose monitoring (CGM) on health-related quality of life (HRQOL), treatment satisfaction (TS) medical resource use, and indirect costs in the SWITCH study. SWITCH ... [more ▼]

To investigate the impact of continuous glucose monitoring (CGM) on health-related quality of life (HRQOL), treatment satisfaction (TS) medical resource use, and indirect costs in the SWITCH study. SWITCH was a multicentre, randomized, crossover study. Patients with type 1 diabetes (n = 153) using continuous subcutaneous insulin infusion (CSII) were randomized to a 12 month sensor-On/Off or sensor-Off/On sequence (6 months each treatment), with a 4-month washout between periods. HRQOL in children and TS in adults were measured using validated questionnaires. Medical resource utilization data were collected. In adults, TS was significantly higher in the sensor-On arm, and there were significant improvements in ratings for treatment convenience and flexibility. There were no clinically significant differences in children’s HRQOL or parents’ proxy ratings. The incidence of severe hypoglycaemia, unscheduled visits, or diabetes-related hospitalizations did not differ significantly between the two arms. Adult patients made fewer telephone consultations during the sensor-On arm; children’s caregivers made similar numbers of telephone consultations during both arms, and calls were on average only 3 min longer during the sensor-On arm. Regarding indirect costs, children with [70 % sensor usage missed fewer school days, compared with the sensor-Off arm (P = 0.0046) but there was no significant difference in the adults days of work off. The addition of CGM to CSII resulted in better metabolic control without imposing an additional burden on the patient or increased medical resource use, and offered the potential for cost offsets. [less ▲]

Impact of IDDM2 on disease pathogenesis and progression in children with newly diagnosed type 1 diabetes: Reduced insulin antibody titres and preserved beta cell function

in Diabetologia (2006), 49(1), 71-74

Aims/hypothesis: The insulin-dependent diabetes mellitus 2 gene (IDDM2) is a type 1 diabetes susceptibility locus contributed to by the variable number of tandem repeats (VNTR) upstream of the insulin ... [more ▼]

Aims/hypothesis: The insulin-dependent diabetes mellitus 2 gene (IDDM2) is a type 1 diabetes susceptibility locus contributed to by the variable number of tandem repeats (VNTR) upstream of the insulin gene (INS). We investigated the association between INS VNTR class III alleles (-23HphIA/T) and both insulin antibody presentation and residual beta cell function during the first year after diagnosis in 257 children with type 1 diabetes. Materials and methods: To estimate C-peptide levels and autoantibody presentation, patients underwent a meal-stimulated C-peptide test 1, 6, and 12 months after diagnosis. The insulin -23HphIA/T variant was used as a marker of class III alleles and genotyped by PCR-RFLP. Results: The insulin antibody titres at 1 and 6 months were significantly lower in the class III/III and class I/III genotype groups than in the class I/I genotype group (p = 0.01). Class III alleles were also associated with residual beta cell function 12 months after diagnosis and independently of age, sex, BMI, insulin antibody titres, and HLA-risk genotype group (p = 0.03). The C-peptide level was twice as high among class III/III genotypes as in class I/I and class I/III genotypes (319 vs 131 and 166 pmol/l, p=0.01). Furthermore, the class III/III genotype had a 1.1% reduction in HbA1c after adjustment for insulin dose (p = 0.04). Conclusions/interpretation: These findings suggest a direct connection in vivo between INS VNTR class III alleles, a decreased humoral immune response to insulin, and preservation of beta cell function in recent-onset type 1 diabetes. © Springer-Verlag 2005. [less ▲]

Impacts of socioeconomic, Family, School, Behavioral and Mental Difficulties on Suicide attempts in Youth

in The bio-psycho-social model: the futur of psychiatry (2013)

This study may help participants to recognize factors influencing suicide attempt which have to be assessed/monitored in boys and girls. Purpose: To assess the impacts of socioeconomic factors, alcohol ... [more ▼]

This study may help participants to recognize factors influencing suicide attempt which have to be assessed/monitored in boys and girls. Purpose: To assess the impacts of socioeconomic factors, alcohol/tobacco/cannabis/hard drugs uses, repeating a school-year, sustained physical/verbal violence, sexual abuse, depressive symptoms, and involvement in violence on suicide attempt among boys and girls in early adolescents. Methods: The sample included 1,559 middle-school students from north-eastern France (778 boys and 781 girls, mean age 13.5, SD 1.3), who completed a self-administered questionnaire including gender, birth date, father’s occupation, parents’ education, nationality, income, social supports (9-item scale), and lifetime history reconstruction of parents’ separation/divorce/death, alcohol/tobacco/ cannabis/hard drugs uses, repeating a school-year, sustained physical/verbal violence (20-item scale), sexual abuse, depressive symptoms (Kandel scale), involvement in violence (11-item scale), and suicide attempts. Data were analyzed using Cox regression models. Results: Lifetime suicide attempt affected 7.2% of boys and 12.5% of girls (p<0.001). Among boys, the factors with significant crude hazard ratio cHR were: insufficient income (2.29), alcohol use (2.33), tobacco use (3.76), hard drugs use (4.48), depressive symptoms (3.60), sustained physical/verbal violence (2.72), sexual abuse (4.30), involvement in violence (3.16), and lack of social support (2.64 for score 1-2, 3.08 for score 3+, vs. score 0). Full model including all factors retained only insufficient income (adjusted hazard ratio aHR 2.11), alcohol use (1.99), depressive symptoms (3.29), and involvement in violence (2.64). Among girls, the factors with significant cHR were: parents’ separation/divorce (2.44), insufficient income (2.23), low parents’ education (1.86), repeating a school-year (2.56), alcohol use (2.04), tobacco use (5.19), cannabis use (3.72), hard drugs use (11.65), depressive symptoms (3.51), sustained physical/verbal violence (1.71), sexual abuse (8.09), involvement in violence (2.04), and lack of social support (3.46 for score 1-2, 6.92 for score 3+, vs. score 0). Full model retained only parents’ separation/divorce (aHR 1.56), repeating a school-year (1.98), alcohol use (1.58), tobacco use (3.60), depressive symptoms (1.86), sexual abuse (6.60), and lack of social support (2.62 for score 1-2 and 4.38 for score 3+, vs. score 0). Compared with boys, girls had a significant cHR of 1.74 which decreased to 1.57 when controlling for all covariates (contribution 23%). Conclusion: This study has achieved our objectives to identify a wide range of socioeconomic, family, school, behavioral and mental difficulties generating suicide attempt among boys and girls in early adolescence. Our findings are original. They reported their causal relationships, the knowledge of which may help public policy preventing suicide attempt. [less ▲]

Impaired glucose tolerance and insulin resistance in heart failure: underrecognized and undertreated?

in Journal of cardiac failure (2010), 16(9), 761-8

BACKGROUND: A link between diabetes mellitus (DM) and heart failure (HF) has been well-recognized for more than a century. HF is also closely linked to abnormal glucose regulation (AGR) and insulin ... [more ▼]

BACKGROUND: A link between diabetes mellitus (DM) and heart failure (HF) has been well-recognized for more than a century. HF is also closely linked to abnormal glucose regulation (AGR) and insulin resistance (IR) in patients without DM and, similarly, these conditions commonly coexist. In epidemiological studies, each condition appears to predict the other. The prevalence of AGR/IR in HF patients without DM is significantly underrecognized and, as yet, the optimal method for screening for these abnormalities in the outpatient setting is unclear. METHODS AND RESULTS: The purpose of this review is to overview the prevalence and prognostic impact of AGR and IR in HF patients without DM and discuss potential pathophysiological pathways that link these conditions with HF. The severity of glucose intolerance in patients with HF correlates with functional and clinical severity of HF and is an independent predictor of an adverse outcome. It is thought that changes in cardiac metabolism, including a switch from glucose metabolism toward fatty acid metabolism, may in part contribute to the pathophysiological processes associated with HF patients with AGR/IR. CONCLUSIONS: We discuss how pharmacological targeting of metabolic pathways in the myocardium of these patients with HF may represent novel therapeutic strategies in these at-risk patients. [less ▲]

Impaired relaxation of the hypertrophied myocardium is potentiated by angiotensin II.

in Journal of hypertension. Supplement : official journal of the International Society of Hypertension (1989), 7(6), 104-5

Relaxation delay is an important feature of hypertensive heart disease which impairs diastolic coronary flow and ventricular filling and therefore contributes to heart failure. We investigated the ... [more ▼]

Relaxation delay is an important feature of hypertensive heart disease which impairs diastolic coronary flow and ventricular filling and therefore contributes to heart failure. We investigated the hypothesis that impaired relaxation is a property of the myocardium, rather than the consequence of ischaemia or interstitial fibrosis. A new videomicroscope system was used to define the contraction-relaxation cycle of isolated cardiac myocytes from spontaneously hypertensive rats (SHR) and normotensive control (Wistar-Kyoto, WKY) rats. The SHR cells showed a marked relaxation delay. Angiotensin II (Ang II) increased the contraction maximum by about 35% in WKY rats and induced a relaxation delay. In SHR Ang II greatly potentiated this relaxation delay. Our results demonstrate that impairment of relaxation is a property of the single cardiomyocyte. Angiotensin II induces a relaxation delay that is independent of blood pressure. The combination of hypertrophy and high levels of Ang II potentiates relaxation impairment and may therefore contribute to hypertensive left ventricular failure. [less ▲]

Implantation of electrodes for deep brain stimulation of the subthalamic nucleus in advanced Parkinson's disease with the aid of intraoperative microrecording under general anesthesia.

in Neurosurgery (2006), 59(5), 11381138

OBJECTIVE: Deep brain stimulation (DBS) is widely accepted in the treatment of advanced Parkinson's disease (PD) and other movement disorders. The standard implantation procedure is performed under local ... [more ▼]

OBJECTIVE: Deep brain stimulation (DBS) is widely accepted in the treatment of advanced Parkinson's disease (PD) and other movement disorders. The standard implantation procedure is performed under local anesthesia (LA). Certain groups of patients may not be eligible for surgery under LA because of clinical reasons, such as massive fear, reduced cooperativity, or coughing attacks. Microrecording (MER) has been shown to be helpful in DBS surgery. The purpose of this study was to evaluate the feasibility of MER for DBS surgery under general anesthesia (GA) and to compare the data of intraoperative MER as well as the clinical data with that of the current literature of patients undergoing operation under LA. CLINICAL PRESENTATION: The data of nine patients with advanced PD (mean Hoehn and Yahr status, 4.2) who were operated with subthalamic nucleus (STN) DBS under GA, owing to certain clinical circumstances ruling out DBS under LA, were retrospectively analyzed. All operations were performed under analgosedation with propofol or remifentanil and intraoperative MER. For MER, remifentanil was ceased completely and propofol was lowered as far as possible. INTERVENTION: The STN could be identified intraoperatively in all patients with MER. The typical bursting pattern was identified, whereas a widening of the baseline noise could not be as adequately detected as in patients under LA. The daily off phases of the patients were reduced from 50 to 17%, whereas the Unified Parkinson's Disease Rating Scale III score was reduced from 43 (preoperative, medication off) to 19 (stimulation on, medication off) and 12 (stimulation on, medication on). Two patients showed a transient neuropsychological deterioration after surgery, but both also had preexisting episodes of disorientation. One implantable pulse generator infection was noticed. No further significant clinical complications were observed. CONCLUSION: STN surgery for advanced PD with MER guidance is possible with good clinical results under GA. Intraoperative MER of the STN region can be performed under GA with a special anesthesiological protocol. In this setting, the typical STN bursting pattern can be identified, whereas the typical widening of the background noise baseline while entering the STN region is obviously absent. This technique may enlarge the group of patients eligible for STN surgery. Although the clinical improvements and parameter settings in this study were within the range of the current literature, further randomized controlled studies are necessary to compare the results of STN DBS under GA and LA, respectively. [less ▲]

Improved Parkinson’s disease classification from diffusion MRI data by Fisher vector descriptors

in Improved Parkinson’s disease classification from diffusion MRI data by Fisher vector descriptors (2015, October)

Due to the complex clinical picture of Parkinson’s disease (PD), the reliable diagnosis of patients is still challenging. A promising approach is the structural characterization of brain areas affected in ... [more ▼]

Due to the complex clinical picture of Parkinson’s disease (PD), the reliable diagnosis of patients is still challenging. A promising approach is the structural characterization of brain areas affected in PD by diffusion magnetic resonance imaging (dMRI). Standard classification methods depend on an accurate non-linear alignment of all images to a common reference template, and are challenged by the resulting huge dimensionality of the extracted feature space. Here, we propose a novel diagnosis pipeline based on the Fisher vector algorithm. This technique allows for a precise encoding into a high-level descriptor of standard diffusion measures like the fractional anisotropy and the mean diffusivity, extracted from the regions of interest (ROIs) typically involved in PD. The obtained low dimensional, fixed-length descriptors are independent of the image alignment and boost the linear separability of the problem in the description space, leading to more efficient and accurate diagnosis. In a test cohort of 50 PD patients and 50 controls, the implemented methodology outperforms previous methods when using a logistic linear regressor for classification of each ROI independently, which are subsequently combined into a single classification decision. [less ▲]