Search results for "defect"
showing 10 items of 879 documents
Imaging the local charge environment of nitrogen-vacancy centers in diamond
2018
Characterizing the local internal environment surrounding solid-state spin defects is crucial to harnessing them as nanoscale sensors of external fields. This is especially germane to the case of defect ensembles which can exhibit a complex interplay between interactions, internal fields and lattice strain. Working with the nitrogen-vacancy (NV) center in diamond, we demonstrate that local electric fields dominate the magnetic resonance behavior of NV ensembles at low magnetic field. We introduce a simple microscopic model that quantitatively captures the observed spectra for samples with NV concentrations spanning over two orders of magnitude. Motivated by this understanding, we propose an…
Conduct disorder and ADHD: evaluation of conduct problems as a categorical and quantitative trait in the international multicentre ADHD genetics stud…
2008
Contains fulltext : 71374.pdf (Publisher’s version ) (Closed access) Attention-deficit/hyperactivity disorder (ADHD) is typically characterized by inattention, excessive motor activity, impulsivity, and distractibility. Individuals with ADHD have significant impairment in family and peer relations, academic functioning, and show high co-morbidity with a wide range of psychiatric disorders including oppositional defiant disorder (ODD), conduct disorder (CD), anxiety disorder, depression, substance abuse, and pervasive developmental disorder (PDD). Family studies suggest that ADHD + CD represents a specific subtype of the ADHD disorder with familial risk factors only partly overlapping with t…
Meta-analysis of genome-wide linkage scans of attention deficit hyperactivity disorder
2008
Contains fulltext : 69243.pdf (Publisher’s version ) (Closed access) Genetic contribution to the development of attention deficit hyperactivity disorder (ADHD) is well established. Seven independent genome-wide linkage scans have been performed to map loci that increase the risk for ADHD. Although significant linkage signals were identified in some of the studies, there has been limited replications between the various independent datasets. The current study gathered the results from all seven of the ADHD linkage scans and performed a Genome Scan Meta Analysis (GSMA) to identify the genomic region with most consistent linkage evidence across the studies. Genome-wide significant linkage (P(S…
No association between two polymorphisms of the serotonin transporter gene and combined type attention deficit hyperactivity disorder.
2008
Contains fulltext : 71091.pdf (Publisher’s version ) (Closed access) Several independent studies have reported association between serotonin transporter gene (SLC6A4) polymorphisms and attention deficit hyperactivity disorder (ADHD). Five studies found evidence for association between the long-allele of a 44-bp insertion/deletion polymorphism (5-HTTLPR) and ADHD. Another two studies corroborated this finding while a further six studies did not find such an association. For a second polymorphism within the gene, a variable number tandem repeat (VNTR) within intron 2, one study demonstrated that the 12/12 genotype was significantly less frequent in ADHD cases compared to controls, while a sec…
Usher syndrome: molecular links of pathogenesis, proteins and pathways.
2006
Contains fulltext : 50437.pdf (Publisher’s version ) (Closed access) Usher syndrome is the most common form of deaf-blindness. The syndrome is both clinically and genetically heterogeneous, and to date, eight causative genes have been identified. The proteins encoded by these genes are part of a dynamic protein complex that is present in hair cells of the inner ear and in photoreceptor cells of the retina. The localization of the Usher proteins and the phenotype in animal models indicate that the Usher protein complex is essential in the morphogenesis of the stereocilia bundle in hair cells and in the calycal processes of photoreceptor cells. In addition, the Usher proteins are important in…
Human cytochrome P450 reductase can act as a source of endogenous oxidative DNA damage and genetic instability.
2005
Studies with repair-deficient mice and other experiments suggest that oxidative DNA modifications are generated in all types of cells even under physiological conditions and that this type of endogenous DNA damage contributes to spontaneous cancer incidence. However, the cellular sources of reactive oxygen species that are relevant for nuclear oxidative DNA damage are largely unknown. Here, we report that expression of human NADPH-cytochrome P450 reductase (hOR) in cultured V79 Chinese hamster cells gives rise to elevated basal levels of oxidative purine modifications after depletion of glutathione. Also, the basal levels of micronuclei are increased in the hOR-expressing cells, and again t…
Defects in glasses
1995
Abstract The absence of long range order in the glass structure allows to define only point defects in these materials. They are: 1) intrinsic defects—atomic size local deviation from short range order; 2) impurity defects—isolated impurity atoms or ions in the glass network; 3) intrinsic impurity defects—complexes consisting of the impurity atoms chemically bonded to one of the intrinsic defect atoms. The latter defects are characteristic for the doped glasses. Presence of point defects in glasses introduces new spectroscopic properties of these solid materials. Defect generation, interaction and recombination reactions resulting from the external influence causes the glass spectroscopic p…
DNA damage by bromate: Mechanism and consequences
2005
Abstract Exposure of mammalian cells to bromate (BrO3−) generates oxidative DNA modifications, in particular 7,8-dihydro-8-oxo-guanine (8-oxoG). The damaging mechanism is quite unique, since glutathione, which is protective against most oxidants and alkylating agents, mediates a metabolic activation, while bromate itself does not react directly with DNA. Neither enzymes nor transition metals are required as catalysts in the activation. The ultimate DNA damaging species has not yet been established, but experiments under cell-free conditions suggest that neither molecular bromine nor reactive oxygen species such as superoxide, hydrogen peroxide or singlet oxygen are involved. Rather bromine …
Pränatale Diagnostik der Sialidose, eines Defektes des lysosomalen Enzyms Neuraminidase
1988
Die Sialidose, eine lysosomale Speicherkrankheit aus der Gruppe der Oligosaccharidosen, ist ein genetischer Enzymdefekt mit stark eingeschrankter Lebenserwartung des betroffenen Kindes. Nach vorheriger Geburt eines an dieser Erkrankung verstorbenen Kindes gelang mit Hilfe der biochemischen Analyse von Amnionzellen der korrekte pranatale Ausschlus einer Sialidose unter Voraussage eines heterozygoten Ubertragerstatus. Aus nicht geklarter Ursache war das Wachstum sowohl der Amnionzellen als auch der postnatal untersuchten Fibroblasten deutlich vermindert. Diese Beobachtung sollte bei weiteren pranatalen Untersuchungen uberpruft werden. Die Moglichkeit der pranatalen Diagnostik einer Sialidose …
Características de los recién nacidos tras fecundación in vitro
2009
Resumen: Objetivo: determinar en una unidad neonatal de nivel II la frecuencia de nacimientos tras fecundación in vitro (FIV) incluyendo FIV-ICSI (intracytoplasmic sperm injection) y comparar sus características con los de fecundación natural (FN), según sean gemelares o únicos. Pacientes y método: estudio prospectivo mediante revisiones fetales desde la semana 12 de gestación tras FIV, al nacer y al año de vida. Del 1 de enero de 2004 al 31 de marzo de 2007 nacieron 7.008 recién nacidos (RN), 113 tras FIV y 6.895 por FN. Resultados: la gemelaridad es del 2,4% en FN y el 56,6% en FIV (p<0,001). La edad materna media en únicos es 28±9 años en FN y 36±4 en FIV (p<0,05); en gemelares es 29±10 …