Discontinuous presentation of ambiguous figures: how interstimulus-interval durations affect reversal dynamics and ERPs

If we observe an ambiguous figure, our percept is unstable and alternates between the possible interpretations. Periodically interrupting the presentation sizably modulates the spontaneous reversal rate. We here studied event-related potential (ERP) correlates of the neural processes underlying these strong modulations. An ambiguous Necker stimulus was presented discontinuously with four randomly varying interstimulus intervals (ISI; 14, 43, 130, 390 ms) while participants indicated perceptual reversals. EEG was selectively averaged with respect to the participants' percept and ISI. ERP traces varied markedly between ISIs. A simple model explained a major part of this variation and showed that the ISI-dependent ERP modulation occurs after disambiguation has already taken place. We suggest that perceptual stability (or reversal) depends on a system state, slowly changing from one reversal to the next. ISI can shift this state on a scale between stability and instability.     

Disruption of EXOC6B in a patient with developmental delay,epilepsy, and a de novo balanced t(2;8) translocation

Most balanced chromosomal aberrations are not associated with a clinical phenotype, however, in some patients they may disrupt gene structure. With the development of various next-generation sequencing techniques, fast and specific analyses of the breakpoint regions of chromosomal rearrangements are possible. Here, we report on a 19-year-old woman with a de novo balanced translocation t(2;8)(p13.2;q22.1) and a severe clinical phenotype including intellectual disability, epilepsy, behavioral features resembling autism, and minor dysmorphic features. By next-generation sequencing, we defined the breakpoints and found disruption of the exocyst complex component 6B (EXOC6B) gene in intron 1 on chromosome 2p13.2 involving two Alu elements with a homology of 81%. No gene was found at the respective breakpoint on chromosome 8. Expression analysis of the EXOC6B in blood lymphocytes and buccal smear revealed reduced expression in the patient in comparison with the control. Our findings in combination with one recently published case and one other patient listed in DECIPHER v5.1 indicate EXOC6B as a gene relevant for intellectual development and electrophysiological stability.     

Probing the biofunctionality of biotinylated hyaluronan and chondroitin sulfate by hyaluronidase degradation and aggrecan interaction

Molecular interactions involving glycosaminoglycans (GAGs) are important for biological processes in the extracellular matrix (ECM) and at cell surfaces, and also in biotechnological applications. Enzymes in the ECM constantly modulate the molecular structure and the amount of GAGs in our tissues. Specifically, the changeable sulfation patterns of many GAGs are expected to be important in interactions with proteins. Biotinylation is a convenient method for immobilizing molecules to surfaces. When studying interactions at the molecular, cell and tissue level, the native properties of the immobilized molecule, i.e. its biofunctionality, need to be retained upon immobilization. Here, the GAGs hyaluronan (HA) and chondroitin sulfate (CS), and synthetically sulfated derivatives of the two, were immobilized using biotin-streptavidin binding. The degree of biotinylation and the placement of biotin groups (end-on/side-on) were varied. The introduction of biotin groups could have unwanted effects on the studied molecule, but this aspect that is not always straightforward to evaluate. Hyaluronidase, an enzyme that degrades HA and CS in the ECM, was investigated as a probe to evaluate the biofunctionality of the immobilized GAGs, using both quartz crystal microbalance and high-performance liquid chromatography. Our results showed that end-on biotinylated HA was efficiently degraded by hyaluronidase, whereas already a low degree of side-on biotinylation destroyed the degrading ability of the enzyme. Synthetically introduced sulfate groups also had this effect. Hence hyaluronidase degradation is a cheap and easy way to investigate how molecular function is influenced by the introduced functional groups. Binding experiments with the proteoglycan aggrecan emphasized the influence of protein size and surface orientation of the GAGs for in-depth studies of GAG behavior.     

Glatiramer acetate attenuates the pro‐migratory profile of adhesion molecules on various immune cell subsets in multiple sclerosis

An altered expression pattern of adhesion molecules (AM) on the surface of immune cells is a premise for their extravasation into the central nervous system (CNS) and the formation of acute brain lesions in multiple sclerosis (MS). We evaluated the impact of glatiramer acetate (GA) on cell‐bound and soluble AM in the peripheral blood of patients with relapsing–remitting MS (RRMS). Fifteen patients treated de novo with GA were studied on four occasions over a period of 12 months. Surface levels of intracellular cell adhesion molecule (ICAM)‐1, ICAM‐3, lymphocyte function‐associated antigen (LFA)‐1 and very late activation antigen (VLA)‐4 were assessed in T cells (CD3⁺CD8⁺, CD3⁺CD4⁺), B cells, natural killer (NK) cells, natural killer T cells (NK T) and monocytes by five‐colour flow cytometry. Soluble E‐selectin, ICAM‐1, ICAM‐3, platelet endothelial cell adhesion molecule (PECAM)‐1, P‐selectin and vascular cell adhesion molecule (VCAM)‐1 were determined with a fluorescent bead‐based immunoassay. The pro‐migratory pattern in RRMS was verified by comparison with healthy controls and was characterized by up‐regulation of LFA‐1 (CD3⁺CD4⁺ T cells, B cells), VLA‐4 (CD3⁺CD8⁺ T cells, NK cells), ICAM‐1 (B cells) and ICAM‐3 (NK cells). Effects of GA treatment were most pronounced after 6 months and included attenuated levels of LFA‐1 (CD3⁺CD4⁺) and VLA‐4 (CD3⁺CD4⁺, CD3⁺CD8⁺, NK, NK T, monocytes). Further effects included lowering of ICAM‐1 and ICAM‐3 levels in almost all immune cell subsets. Soluble AM levels in RRMS did not differ from healthy controls and remained unaltered after GA treatment. The deregulated pro‐migratory expression profile of cell‐bound AM is altered by GA treatment. While this alteration may contribute to the beneficial action of the drug, the protracted development and unselective changes indicate more secondary immune regulatory phenomena related to these effects.     

IL13 variants are associated with total serum IgE and early sensitization to food allergens in children with atopic dermatitis

Increased total and specific serum immunoglobulin E (IgE) levels are common characteristics of atopic diseases and their basal production is proposed to be under strong genetic control. Interleukin 13 (IL13) variants have been consistently associated with total serum IgE levels in white populations with a strongest association in non‐atopics. The aim of this study was to test the IL13 p.R130Q and c.1‐1111C>T variants in children with atopic dermatitis (AD) for associations with total serum IgE and early sensitization to common food and inhalant allergens and with asthma. We included 453 children with AD [participants of the Early Treatment of the Atopic Child (ETAC) study] that were followed from the age of 12–24 months for 3 yr. Total and specific IgE were determined at four time points. We genotyped the IL13 p.R130Q and c.1‐1111C>T variants by melting curve analysis. In children up to 4 yr of age, the 130Q allele was related to slightly higher total IgE levels compared to heterozygotes and 130R homozygotes. More importantly, both IL13 variants were significantly associated with sensitization to food allergens, with most significant results for sensitization to egg (p = 0.0001). Although early sensitization to hen’s egg represents a strong risk factor for subsequent sensitization to inhalant allergens and asthma, the investigated IL13 variants were not associated with these phenotypes at the age of 48–60 months. In summary IL13 variants contribute to elevated levels of total serum IgE in young atopic children and are strongly associated with sensitization to food allergens, particularly to hen’s egg. These findings suggest that IL13 variants play a major role not only in non‐cognate but also in allergen specific IgE synthesis.     

IRF6 gene variants in Central European patients with non‐syndromic cleft lip with or without cleft palate

Variants in the interferon regulatory factor 6 (IRF6) gene have repeatedly been associated with non‐syndromic cleft lip with or without cleft palate (NSCL/P). A recent study has suggested that the functionally relevant variant rs642961 is the underlying cause of the observed associations. We genotyped rs642961 in our Central European case–control sample of 460 NSCL/P patients and 952 controls. In order to investigate whether other IRF6 variants contribute independently to the etiology of NSCL/P, we also genotyped the non‐synonymous coding variant V274I (rs2235371) and five IRF6‐haplotype tagging single nucleotide polymorphisms (SNPs). A highly significant result was observed for rs642961 (P = 1.44 × 10^?6) in our sample. The odds ratio was 1.75 [95% confidence interval (CI): 1.38–2.22] for the heterozygous genotype and 1.94 (95% CI: 1.21–3.10) for the homozygous genotype, values that are similar to those reported in a previously published family‐based study. Our results thus confirm the involvement of the IRF6 variant, rs642961, in the etiology of NSCL/P in the Central European population. We also found evidence suggestive of an independent protective effect of the coding variant V274I. In order to understand fully the genetic architecture of the IRF6 locus, it will be necessary to conduct additional SNP‐based and resequencing studies using large samples of patients.     

Homozygous nonsense and frameshift mutations of the ACTH receptor in children with familial glucocorticoid deficiency (FGD) are not associated with long-term mineralocorticoid deficiency

Objective  Familial glucocorticoid deficiency (FGD) is a rare autosomal recessive disease characterized by isolated glucocorticoid deficiency with preserved mineralocorticoid secretion. Mutations in the ACTH receptor (MC2R) account for approximately 25% of all FGD cases, but since these are usually missense mutations, a degree of receptor function is frequently retained. A recent report, however, suggested that disturbances in the renin–aldosterone axis were seen in some patients with potentially more severe MC2R mutations. Furthermore, MC2R knock out mice have overt aldosterone deficiency and hyperkalaemia despite preservation of a normal zona glomerulosa. We wished to determine whether a group of patients with severe nonsense mutations of the MC2R exhibited evidence of mineralocorticoid deficiency, thereby challenging the conventional diagnostic feature of FGD which might result in diagnostic misclassification.
Design  Clinical review of patients with nonsense MC2R mutations.
Patients  Between 1993 and 2008, 164 patients with FGD were screened for mutations in the MC2R. Totally 42 patients (34 families) were found to have mutations in the MC2R. Of these, 6 patients (4 families) were found to have homozygous nonsense or frameshift mutations.
Results  Mild disturbances in the renin–angiotensin–aldosterone axis were noted in four out of six patients, ranging from slightly elevated plasma renin levels to low aldosterone levels, although frank mineralocorticoid deficiency or electrolyte disturbance were not found. No patient required fludrocortisone replacement.
Conclusion  Severe nonsense and frameshift MC2R mutations are not associated with clinically significant mineralocorticoid deficiency and are thus unlikely to require long-term mineralocorticoid replacement.     

Malaria morbidity,treatment-seeking behaviour,and mortality in a cohort of young children in rural Burkina Faso

OBJECTIVE: To describe the pattern of fever-associated morbidity, treatment-seeking behaviour for fever episodes, and cause-specific mortality in young children of a malaria-holoendemic area in rural Burkina Faso. METHODS: In a longitudinal community-based intervention study, 709 representative children aged 6-31 months were followed daily over 6 months (including the main malaria transmission period) through village-based field staff. RESULTS: Of 1848 disease episodes, 1640 (89%) were fever episodes, and of those, 894 (55%) were attributed to malaria (fever + > or =5000 parasites/microl). Eighty-five percent of fever episodes were treated, mainly with chloroquine and paracetamol, 69% of treatments took place in households, 16% in local health centres, 13% in villages, and 1% in hospitals. Treatment-seeking in a health centre or hospital was associated with accessibility and disease severity. Cerebral malaria and malnutrition-associated diarrhoea were the most frequently diagnosed causes of death. While most children with a post-mortem diagnosis of diarrhoea had not received any treatment, children who died of malaria had often received insufficient treatment. In particular, there was a lack of an appropriate second-line treatment at formal health services after chloroquine treatment had failed to resolve symptoms. CONCLUSIONS: These findings call for more effective prevention and treatment of malaria, malnutrition and diarrhoea in rural African communities, as well as for better supervision of existing malaria treatment guidelines in formal health services.     

X-ray digital subtraction angiography with 1 mol/L gadobutrol: results from a comparative porcine study With iodinated contrast agents

RATIONALE AND OBJECTIVES: To evaluate prospectively diagnostic accuracy of 1 mol/L gadobutrol as a contrast agent for intraarterial x-ray digital subtraction angiography (DSA) in comparison to iodinated, nonionic contrast media and 0.5 mol/L gadolinium-DTPA. METHODS: Flush arteriograms (ascending, descending, abdominal aorta, iliac, and femoral arteries) and selective angiograms (carotid, renal, and visceral arteries) were obtained from bilateral femoral arterial access (5 F sheaths) in 10 domestic pigs (70 kg body weight). Digital subtracted angiograms were obtained during injection of undiluted 1 mol/L gadobutrol, 300 mg I/mL iopromide, or 0.5 mol/L gadopentetate. Injection parameters (volume and velocity) were similar for all three contrast agents. In paired arteries, two different contrast media were used during the same angiographic run. Diagnostic quality and accuracy of the angiograms were evaluated on a three-step scale by three independent blinded investigators. RESULTS: Sufficient nonselective angiographic images were obtained in 90% of cases using iodinated contrast material. Gadobutrol achieved sufficient nonselective angiograms in 64%. Selective angiograms were sufficient in 98% using iodinated contrast material, 90% using 1 mol/L Gadobutrol and 48% using 0.5 mol/L Gd-DTPA. Adverse reactions to any of the used contrast agents were not noted. CONCLUSION: One mol/L Gadobutrol solution allows x-ray digital subtraction angiography with a diagnostic accuracy equivalent to 300 mg/mL iodinated contrast media, if selective injections are performed. Flush aortograms are of inferior image quality to iodinated contrast material.     

Phases of A beta-deposition in the human brain and its relevance for the development of AD

BACKGROUND: The deposition of the amyloid beta protein (Abeta) is a histopathologic hallmark of AD. The regions of the medial temporal lobe (MTL) are hierarchically involved in Abeta-deposition. OBJECTIVE: To clarify whether there is a hierarchical involvement of the regions of the entire brain as well and whether there are differences in the expansion of Abeta-pathology between clinically proven AD cases and nondemented cases with AD-related pathology, the authors investigated 47 brains from demented and nondemented patients with AD-related pathology covering all phases of beta-amyloidosis in the MTL (AbetaMTL phases) and four control brains without any AD-related pathology. METHODS: Abeta deposits were detected by the use of the Campbell-Switzer silver technique and by immunohistochemistry in sections covering all brain regions and brainstem nuclei. It was analyzed how often distinct regions exhibited Abeta deposits. RESULTS: In the first of five phases in the evolution of beta-amyloidosis Abeta deposits are found exclusively in the neocortex. The second phase is characterized by the additional involvement of allocortical brain regions. In phase 3, diencephalic nuclei, the striatum, and the cholinergic nuclei of the basal forebrain exhibit Abeta deposits as well. Several brainstem nuclei become additionally involved in phase 4. Phase 5, finally, is characterized by cerebellar Abeta-deposition. The 17 clinically proven AD cases exhibit Abeta-phases 3, 4, or 5. The nine nondemented cases with AD-related Abeta pathology show Abeta-phases 1, 2, or 3. CONCLUSIONS: Abeta-deposition in the entire brain follows a distinct sequence in which the regions are hierarchically involved. Abeta-deposition, thereby, expands anterogradely into regions that receive neuronal projections from regions already exhibiting Abeta. There are also indications that clinically proven AD cases with full-blown beta-amyloidosis may be preceded in early stages by nondemented cases exhibiting AD-related Abeta pathology.