Display omitted
•In this study we quantitatively demonstrated the effects induced by amorphous SiO2-NPs in biologically relevant samples.•Utilizing a rapid HILIC-ESI-MS technique we found an approx. ...50% DPPC decrease in cell culture medium during exposure to amorphous SiO2-NPs.•A substantial affinity of small SiO2-NPs to DPPC standard solution compared to bigger SiO2-NPs was not confirmed for biological specimens.•HILIC-ESI-MS revealed that A549 cells internalized DPPC during growth in medium complemented with DPPC containing serum.
This paper reports a rapid HILIC-ESI–MS assay to quantify dipalmitoylphosphatidylcholine (DPPC) as component of lung surfactant for nanosafety studies. The technique was used to investigate the concentration-dependent sorption of DPPC to two-sizes of amorphous SiO2 nanoparticles (SiO2-NPs) in a MeOH:H2O (50/50v/v) mixture and in cell culture medium. In MeOH:H2O (50/50v/v), the sorption of DPPC was positively correlated with the nanoparticles concentration. A substantial affinity of small amorphous SiO2-NPs (25nm) to DPPC standard solution compared to bigger SiO2-NPs (75nm) was not confirmed for biological specimens. After dispersion of SiO2-NPs in DPPC containing cell culture medium, the capacity of the SiO2-NPs to bind DPPC was reduced in comparison to a mixture of MeOH:H2O (50/50v/v) regardless from the nanoparticles size.
Furthermore, HILIC-ESI–MS revealed that A549 cells internalized DPPC during growth in serum containing medium complemented with DPPC. This finding was in a good agreement with the potential of alveolar type II cells to recycle surfactant components.
Binding of lipids present in the cell culture medium to amorphous SiO2-NPs was supported by means of HILIC-ESI–MS, TEM and ICP-MS independently.
We report bi-allelic pathogenic HPDL variants as a cause of a progressive, pediatric-onset spastic movement disorder with variable clinical presentation. The single-exon gene HPDL encodes a protein ...of unknown function with sequence similarity to 4-hydroxyphenylpyruvate dioxygenase. Exome sequencing studies in 13 families revealed bi-allelic HPDL variants in each of the 17 individuals affected with this clinically heterogeneous autosomal-recessive neurological disorder. HPDL levels were significantly reduced in fibroblast cell lines derived from more severely affected individuals, indicating the identified HPDL variants resulted in the loss of HPDL protein. Clinical presentation ranged from severe, neonatal-onset neurodevelopmental delay with neuroimaging findings resembling mitochondrial encephalopathy to milder manifestation of adolescent-onset, isolated hereditary spastic paraplegia. All affected individuals developed spasticity predominantly of the lower limbs over the course of the disease. We demonstrated through bioinformatic and cellular studies that HPDL has a mitochondrial localization signal and consequently localizes to mitochondria suggesting a putative role in mitochondrial metabolism. Taken together, these genetic, bioinformatic, and functional studies demonstrate HPDL is a mitochondrial protein, the loss of which causes a clinically variable form of pediatric-onset spastic movement disorder.
The microvascular endothelium of the gut barrier plays a crucial role during inflammation in inflammatory bowel disease. We have modified a commonly used intestinal cell model based on the Caco-2 ...cells by adding microvascular endothelial cells (ISO-HAS-1). Transwell filters were used with intestinal barrier-forming Caco-2 cells on top and the ISO-HAS-1 on the bottom of the filter. The goal was to determine whether this coculture mimics the in vivo situation more closely, and whether the model is suitable to evaluate interactions of, for example, prospective nanosized drug vehicles or contrast agents with this coculture in a physiological and inflamed state as it would occur in inflammatory bowel disease. We monitored the inflammatory responsiveness of the cells (release of IL-8, soluble intercellular adhesion molecule 1, and soluble E-selectin) after exposure to inflammatory stimuli (lipopolysaccharide, TNF-α, INF-γ, IL1-β) and a nanoparticle (Ba/Gd: coprecipitated BaSO
and Gd(OH)
), generally used as contrast agents. The barrier integrity of the coculture was evaluated via the determination of transepithelial electrical resistance and the apparent permeability coefficient (P
) of NaFITC. The behavior of the coculture Caco-1/ISO-HAS-1 was compared to the respective monocultures Caco-2 and ISO-HAS-1. Based on transepithelial electrical resistance, the epithelial barrier integrity of the coculture remained stable during incubation with all stimuli, whereas the P
decreased after exposure to the cytokine mixture (TNF-α, INF-γ, IL1-β, and Ba/Gd). Both the endothelial and epithelial monocultures showed a high inflammatory response in both the upper and lower transwell-compartments. However, in the coculture, inflammatory mediators were only detected on the epithelial side and not on the endothelial side. Thus in the coculture, based on the P
, the epithelial barrier appears to prevent a potential inflammatory overreaction in the underlying endothelial cells. In summary, this coculture model exhibits in vivo-like features, which cannot be observed in conventional monocultures, making the former more suitable to study interactions with external stimuli.
Leukoencephalopathy with brainstem and spinal cord involvement and lactate elevation is a disorder caused by recessive mutations in the gene DARS2, which encodes mitochondrial aspartyl-tRNA ...synthetase. Recent observations indicate that the phenotypic range of the disease is much wider than initially thought. Currently, no treatment is available. The aims of our study were (i) to explore a possible genotype-phenotype correlation; and (ii) to identify potential therapeutic agents that modulate the splice site mutations in intron 2 of DARS2, present in almost all patients. A cross-sectional observational study was performed in 78 patients with two DARS2 mutations in the Amsterdam and Helsinki databases up to December 2012. Clinical information was collected via questionnaires. An inventory was made of the DARS2 mutations in these patients and those previously published. An assay was developed to assess mitochondrial aspartyl-tRNA synthetase enzyme activity in cells. Using a fluorescence reporter system we screened for drugs that modulate DARS2 splicing. Clinical information of 66 patients was obtained. The clinical severity varied from infantile onset, rapidly fatal disease to adult onset, slow and mild disease. The most common phenotype was characterized by childhood onset and slow neurological deterioration. Full wheelchair dependency was rare and usually began in adulthood. In total, 60 different DARS2 mutations were identified, 13 of which have not been reported before. Except for 4 of 42 cases published by others, all patients were compound heterozygous. Ninety-four per cent of the patients had a splice site mutation in intron 2. The groups of patients sharing the same two mutations were too small for formal assessment of genotype-phenotype correlation. However, some combinations of mutations were consistently associated with a mild phenotype. The mitochondrial aspartyl-tRNA synthetase activity was strongly reduced in patient cells. Among the compounds screened, cantharidin was identified as the most potent modulator of DARS2 splicing. In conclusion, the phenotypic spectrum of leukoencephalopathy with brainstem and spinal cord involvement and lactate elevation is wide, but most often the disease has a relatively slow and mild course. The available evidence suggests that the genotype influences the phenotype, but because of the high number of private mutations, larger numbers of patients are necessary to confirm this. The activity of mitochondrial aspartyl-tRNA synthetase is significantly reduced in patient cells. A compound screen established a 'proof of principle' that the splice site mutation can be influenced. This finding is promising for future therapeutic strategies.
Beside the promising application potential of nanotechnologies in engineering, the use of nanomaterials in medicine is growing. New therapies employing innovative nanocarrier systems to increase ...specificity and efficacy of drug delivery schemes are already in clinical trials. However the influence of the nanoparticles themselves is still unknown in medical applications, especially for complex interactions in neural systems. The aim of this study was to investigate in vitro effects of coated silver nanoparticles (cAgNP) on the excitability of single neuronal cells and to integrate those findings into an in silico model to predict possible effects on neuronal circuits.
We first performed patch clamp measurements to investigate the effects of nanosized silver particles, surrounded by an organic coating, on excitability of single cells. We then determined which parameters were altered by exposure to those nanoparticles using the Hodgkin-Huxley model of the sodium current. As a third step, we integrated those findings into a well-defined neuronal circuit of thalamocortical interactions to predict possible changes in network signaling due to the applied cAgNP, in silico.
We observed rapid suppression of sodium currents after exposure to cAgNP in our in vitro recordings. In numerical simulations of sodium currents we identified the parameters likely affected by cAgNP. We then examined the effects of such changes on the activity of networks. In silico network modeling indicated effects of local cAgNP application on firing patterns in all neurons in the circuit.
Our sodium current simulation shows that suppression of sodium currents by cAgNP results primarily by a reduction in the amplitude of the current. The network simulation shows that locally cAgNP-induced changes result in changes in network activity in the entire network, indicating that local application of cAgNP may influence the activity throughout the network.
Surveillance of cerebral palsy in Europe (SCPE) presents the first population-based results on neuroimaging findings in children with cerebral palsy (CP) using a magnetic resonance imaging ...classification system (MRICS).
MRIs of children with CP born between 1999 and 2009 from 18 European countries were analyzed. MRICS identifies patterns of brain pathology according to timing during brain development which was analyzed with respect to CP subtypes and gestational age.
MRIs or written reports from 3,818 children were available. The main clinical characteristics were similar to the 5,415 without such data. Most frequent was predominant white matter injury (49%), followed by predominant gray matter injury (21%). Maldevelopments were found in 11% of cases. Miscellaneous findings were present in 8.5% and normal findings in 10.6%. MRI patterns of children with unilateral spastic, bilateral spastic, and dyskinetic CP were mainly lesional (77, 71, and 59%, respectively), whereas children with ataxic CP had more maldevelopments, miscellaneous, and normal findings (25, 21, and 32%, respectively). In children born preterm, predominant white matter injury was most prevalent (80% in children born <32 weeks of gestation).
Analysis of MRI in the European CP database identified CP as a mainly lesional condition on a large population basis, maldevelopments were relatively uncommon. An exception was ataxic CP. Children born preterm mostly presented with a lesion typical for their gestational age (GA) at birth. The decreasing prevalence of CP in this group suggests that progress in perinatal and neonatal medicine may lead to a reduction of these lesions.
Cerebral palsy (CP) is a disorder of movement and posture and every child with CP has a unique composition of neurological symptoms, motor severity, and associated impairments, constituting the ...functional profile. Although not part of the CP definition, magnetic resonance imaging (MRI) sheds light on the localization, nature, and severity of brain compromise. The MRI classification system (MRICS), developed by the Surveillance of Cerebral Palsy in Europe (SCPE), describes typical MRI patterns associated with specific timing of vulnerability in different areas of the brain. The classification has proven to be reliable and easy to use.
The aim of this study is to apply the MRICS on a large dataset and describe the functional profile associated with the different MRI patterns of the MRICS.
Data on children with CP born in 1999-2009 with a post-neonatal MRI from 20 European registers in the JRC-SCPE Central Registry was included. The CP classification and the MRICS was applied, and The Gross Motor Function Classification (GMFCS) and the Bimanual Fine Motor Function (BFMF) classification were used. The following associated impairments were documented: intellectual impairment, active epilepsy, visual impairment, and hearing impairment. An impairment index was used to characterize severity of impairment load.
The study included 3,818 children with post-neonatal MRI. Distribution of CP type, motor, and associated impairments differed by neuroimaging patterns. Functional profiles associated with neuroimaging patterns were described, and the impairment index showed that bilateral findings were associated with a more severe outcome both regarding motor impairment and associated impairments than unilateral compromise. The results from this study, particularly the differences in functional severity regarding uni- and bilateral brain compromise, may support counseling and service planning of support of children with CP.
We investigate how known differences in myelin architecture between regions along the cortico-spinal tract and frontal white matter (WM) in 19 healthy adolescents are reflected in several ...quantitative MRI parameters that have been proposed to non-invasively probe WM microstructure. In a clinically feasible scan time, both conventional imaging sequences as well as microstructural MRI parameters were assessed in order to quantitatively characterise WM regions that are known to differ in the thickness of their myelin sheaths, and in the presence of crossing or parallel fibre organisation.
We found that diffusion imaging, MR spectroscopy (MRS), myelin water fraction (MWF), Magnetization Transfer Imaging, and Quantitative Susceptibility Mapping were myelin-sensitive in different ways, giving complementary information for characterising WM microstructure with different underlying fibre architecture. From the diffusion parameters, neurite density (NODDI) was found to be more sensitive than fractional anisotropy (FA), underlining the limitation of FA in WM crossing fibre regions. In terms of sensitivity to different myelin content, we found that MWF, the mean diffusivity and chemical-shift imaging based MRS yielded the best discrimination between areas.
Multimodal assessment of WM microstructure was possible within clinically feasible scan times using a broad combination of quantitative microstructural MRI sequences. By assessing new microstructural WM parameters we were able to provide normative data and discuss their interpretation in regions with different myelin architecture, as well as their possible application as biomarker for WM disorders.
To report three unrelated infants with a distinctive phenotype of Leigh-like syndrome, neurogenic muscular atrophy, and hypertrophic obstructive cardiomyopathy. The patients all had a homozygous ...missense mutation in SCO2.
SCO2 encodes a mitochondrial inner membrane protein, thought to function as a copper transporter to cytochrome c oxidase (COX), the terminal enzyme of the respiratory chain. Mutations in SCO2 have been described in patients with severe COX deficiency and early onset fatal infantile hypertrophic cardioencephalomyopathy. All patients so far reported are compound heterozygotes for a missense mutation (E140K) near the predicted CxxxC metal binding motif; however, recent functional studies of the homologous mutation in yeast failed to demonstrate an effect on respiration.
Here we present clinical, biochemical, morphologic, functional, MRI, and MRS data in two infants, and a short report in an additional patient, all carrying a homozygous G1541A transition (E140K).
The disease onset and symptoms differed significantly from those in compound heterozygotes. MRI and muscle morphology demonstrated an age-dependent progression of disease with predominant involvement of white matter, late appearance of basal ganglia lesions, and neurogenic muscular atrophy in addition to the relatively late onset of hypertrophic cardiomyopathy. The copper uptake of cultured fibroblasts was significantly increased.
The clinical spectrum of SCO2 deficiency includes the delayed development of hypertrophic obstructive cardiomyopathy and severe neurogenic muscular atrophy. There is increased copper uptake in patients' fibroblasts indicating that the G1541A mutation effects cellular copper metabolism.
Pontocerebellar hypoplasias (PCH) represent a group of neurodegenerative autosomal recessive disorders with prenatal onset, atrophy or hypoplasia of the cerebellum, hypoplasia of the ventral pons, ...microcephaly, variable neocortical atrophy and severe mental and motor impairments. In two subtypes, PCH2 and PCH4, we identified mutations in three of the four different subunits of the tRNA-splicing endonuclease complex. Our findings point to RNA processing as a new basic cellular impairment in neurological disorders.
PDF
