Detection of egg yolk antibodies reflecting Salmonella enteritidis infections using a surface plasmon resonance biosensor

A surface plasmon resonance (SPR) biosensor assay was developed on the basis of a lipopolysaccharide antigen of Salmonella enterica serovar enteritidis (S. enterica serovar enteritidis) to detect egg yolk antibodies against S. enterica serovar enteritidis. This biosensor assay was compared to two commercial ELISA kits based on LPS antigen and flagellar antigen. A number of 163 egg yolk and combined egg white and yolk samples from chickens experimentally infected with S. enterica serovar enteritidis and 90 egg yolk and combined egg white and yolk samples from uninfected chickens were analyzed. Receiver operating characteristic analysis of the data calculated a diagnostic sensitivity of 82% and a diagnostic specificity of 100%. The within-day coefficient of variation of a positive internal-control egg yolk was 1%. The SPR biosensor assay was able to detect antibodies in a significantly higher percentage of known positive samples than the commercial ELISA's. The anticipated use of the SPR biosensor assay is to determine the S. enterica serovar enteritidis serostatus of non-vaccinated layer hens.     

Smoothelin expression during chicken embryogenesis: detection of an embryonic isoform.

Two isoforms of a novel smooth muscle cell (SMC) -specific cytoskeletal protein, smoothelin, have been described. In the adult chick, the 55-kDa smoothelin-A is expressed in visceral SMC, whereas the 120-kDa smoothelin-B is the major product in vascular SMC. Chicken was chosen to study smoothelin expression during embryogenesis and neonatally. Smoothelin-B was found in vascular SMC from stage 20 onward. In visceral SMC, smoothelin-B was present from stage 29 until hatching. Perinatally, a strong up-regulation of smoothelin synthesis was observed in visceral tissues, coinciding with a switch to the A-isoform. Transient smoothelin synthesis was observed in the somites and the developing heart. Western blotting revealed in these tissues a 62-kDa smoothelin isoform, designated smoothelin-C. Expression of the smoothelin isoforms seems to be strictly controlled with respect to cell type and developmental stage and may be related to the mode of contraction of the different cells.     

Direct Versus Competitive Biosensor Immunoassays for the Detection of (Dihydro)Streptomycin Residues in Milk

A monoclonal antibody (MAb) against dihydrostreptomycin (4G8) was developed and its performance compared with a previously developed MAb against streptomycin (4E2) in biosensor immunoassays (BIAs) using a surface plasmon resonance (SPR)-based biosensor (BIACORE 3000). Direct BIAs for the detection of dihydrostreptomycin (DHS; 583 Da) and streptomycin (STREP; 581 Da) were developed by immobilising the MAbs on the sensor chip (CM5). These direct BIAs were compared with competitive inhibition BIAs, using a STREP- protein conjugate immobilized on the chip. The sensitivities of the direct and competitive BIAs for both drugs in buffer were comparable (10-20 ng ml- 1 at 50% binding or inhibition). With milk, interferences, probably due to the nonspecific binding of proteins to the sensor chips, were observed in both BIAs. These interferences could be largely reduced using ultra filtration (UF) as sample pre-treatment. Another option was the use of a reference flow channel to correct for nonspecific binding. Using this option with five times diluted milk, MAb 4G8 was found to be suited for the direct BIA of both drugs with a limit of detection (LOD) of 20 ng ml- 1 and both MAbs could be applied in the competitive BIA format with similar LODs.     

Epicardial outgrowth inhibition leads to compensatory mesothelial outflow tract collar and abnormal cardiac septation and coronary formation

In the present study, we investigated the modulatory role of the epicardium in myocardial and coronary development. Epicardial cell tracing experiments have shown that epicardium-derived cells are the source of interstitial myocardial fibroblasts, cushion mesenchyme, and smooth muscle cells. Epicardial outgrowth inhibition studies show abnormalities of the compact myocardial layer, myocardialization of cushion tissue, looping, septation, and coronary vascular formation. Lack of epicardial spreading is partly compensated by mesothelial outgrowth over the conotruncal region. Heterospecific epicardial transplant is able to partially rescue the myocardial development, as well as septation and coronary formation.     

No objectively measured sleep disturbances in children with attention‐deficit/hyperactivity disorder

The main goal of this study was to gain more insight into sleep disturbances in children with attention‐deficit/hyperactivity disorder, using objective measures of sleep quality and quantity. The evidence for sleep problems in children with attention‐deficit/hyperactivity disorder thus far is inconsistent, which might be explained by confounding influences of comorbid internalizing and externalizing problems and low socio‐economic status. We therefore investigated the mediating and moderating role of these factors in the association between attention‐deficit/hyperactivity disorder and sleep problems. To control for the effects of stimulant medication use, all participants were tested free of medication. Sixty‐three children with attention‐deficit/hyperactivity disorder and 61 typically developing children, aged 6–13 years, participated. Sleep was monitored for one to three school nights using actigraphy. Parent and teacher questionnaires assessed symptoms of attention‐deficit/hyperactivity disorder, internalizing behaviour, oppositional defiant disorder and conduct disorder. Results showed no differences between the attention‐deficit/hyperactivity disorder and typically developing group in any sleep parameter. Within the attention‐deficit/hyperactivity disorder group, severity of attention‐deficit/hyperactivity disorder symptoms was not related to sleep quality or quantity. Moderation analyses in the attention‐deficit/hyperactivity disorder group showed an interaction effect between attention‐deficit/hyperactivity disorder symptoms and internalizing and externalizing behaviour on total sleep time, time in bed and average sleep bout duration. The results of our study suggest that having attention‐deficit/hyperactivity disorder is not a risk factor for sleep problems. Internalizing and externalizing behaviour moderate the association between attention‐deficit/hyperactivity disorder and sleep, indicating a complex interplay between psychiatric symptoms and sleep.     

Facial emotion recognition impairment predicts social and emotional problems in children with (subthreshold) ADHD

Children with attention-deficit/hyperactivity disorder (ADHD) symptoms often experience social and emotional problems. Impaired facial emotion recognition has been suggested as a possible underlying mechanism, although impairments may depend on the type and intensity of emotions. We investigated facial emotion recognition in children with (subthreshold) ADHD and controls using a novel task with children’s faces of emotional expressions varying in type and intensity. We further investigated associations between emotion recognition accuracy and social and emotional problems in the ADHD group. 83 children displaying ADHD symptoms and 30 controls (6–12 years) completed the Morphed Facial Emotion Recognition Task (MFERT). The MFERT assesses emotion recognition accuracy on four emotions using five expression intensity levels. Teachers and parents rated social and emotional problems on the Strengths and Difficulties Questionnaire. Repeated measures analysis of variance revealed that the ADHD group showed poorer emotion recognition accuracy compared to controls across emotions (small effect). The significant group by expression intensity interaction (small effect) showed that the increase in accuracy with increasing expression intensity was smaller in the ADHD group compared to controls. Multiple regression analyses within the ADHD group showed that emotion recognition accuracy was inversely related to social and emotional problems, but not prosocial behavior. Not only children with an ADHD diagnosis, but also children with subthreshold ADHD experience impairments in facial emotion recognition. This impairment is predictive for social and emotional problems, which may suggest that emotion recognition may contribute to the development of social and emotional problems in these children.

     

Loss of function of the Prx1 and Prx2 homeobox genes alters architecture of the great elastic arteries and ductus arteriosus

Prx1 (MHox) and Prx2 (S8) are non-clustered homeobox genes that are expressed in a complex, mostly mesenchyme-specific pattern throughout embryogenesis. The expression pattern and gene-targeted mice previously revealed a major role for Prx1 in skeletogenesis. In addition, specific and high expression of both Prx genes was reported in the developing cardiovascular system, predominantly in prospective connective tissues of the heart and in the great arteries and veins. We examined embryos of previously generated gene-targeted mice. Prx2-/- mutants were viable and did not show cardiovascular malformations. Intracardiac morphology of Prxl-/- and Prx1/Prx2-combined null mutants also appeared normal throughout development. However, the Prx1-/- and Prx1/Prx2 double-null mutants showed a vascular abnormality with an abnormal positioning and awkward curvature of the aortic arch in addition to a misdirected and elongated ductus arteriosus, and in two of seven combined mutants, an anomalous retro-oesophageal right subclavian artery. Generally, all great arteries appeared to run somewhat tortuously through the surrounding mesenchyme. The vascular histology and vessel wall thickness were normal in all mutants. Prx1-/- and Prx double-gene-targeted mice revealed similar spectra of vascular anomalies, but double mutants appeared to be more seriously affected. The current findings suggest that other genes may compensate for the lossof Prx in the heart, but, in contrast, our data support a role for Prx in the development of vascular and perivascular matrix. Received: 1 April 1999 / Accepted: 1 June 1999