EEG theta and beta power spectra in adolescents with ADHD versus adolescents with ASD + ADHD.

Attention problems are common in youngsters with attention deficit hyperactivity disorder (ADHD) as well as in adolescents with combined autism spectrum disorder (ASD) and ADHD. However, it is unknown whether there is psychophysiological overlap and/or a difference in electroencephalogram (EEG) power spectra between ADHD and comorbid ASD and ADHD (ASD + ADHD), on and off stimulant medication. To explore potential differences and overlap, measures of theta and beta power in adolescents diagnosed with ADHD (n = 33) versus adolescents with combined ASD + ADHD (n = 20), categorized by stimulant medication use (57 % of the total sample), were compared. EEG measures were acquired in three conditions: (1) resting state, eyes closed (2) resting state, eyes open and (3) during an oddball task. In addition, performance on the d2 attention test was analyzed. Adolescents with ADHD displayed more absolute theta activity than adolescents with ASD + ADHD during the eyes open and task conditions, independent of stimulant medication use. In addition, only the adolescents with ADHD showed an association between diminished attention test performance and increased theta in the eyes open condition. Results of the current study suggest that although there is behavioral overlap between ADHD characteristics in adolescents with ADHD and adolescents with combined ASD + ADHD, the underlying psychophysiological mechanisms may be different. Adolescents with ASD + ADHD exhibited fewer of the EEG physiological signs usually associated with ADHD, although there was an overlap in attentional problems between the groups. This may indicate that treatments developed for ADHD work differently in some adolescents with ASD + ADHD and adolescents with ADHD only.

Cardiac reactivity and stimulant use in adolescents with autism spectrum disorders with comorbid ADHD versus ADHD.

A large number of youngsters with autism spectrum disorders (ASD) display comorbid attention deficit/hyperactivity disorder (ADHD) symptoms. However, previous studies are not conclusive whether psychophysiological correlates, like cardiac reactivity, are different for ASD with comorbid ADHD (ASD+) compared to ADHD. Therefore, the current study investigated (dis)similarities in cardiac reactivity and attention task performance. In a clinical sample, adolescents diagnosed with ASD+ (n = 20) versus ADHD (n = 36) and stimulant medication use (56 %) were compared during a baseline with eyes closed and task performance. Results for cardiac reactivity were similar for both diagnostic groups. Stimulant-medicated adolescents showed decreased adaptation of LF/HF ratio and faster reaction times than stimulant-free adolescents. The current study underlines the psychophysiological overlap of ADHD symptoms in adolescents with ASD+ and adolescents with ADHD.

A sol-particle immunoassay for determination of anti-rubella antibodies; development and clinical validation.

A sol-particle immunoassay (SPIA) was developed for determination of anti-rubella antibodies. The test is based on antibody-coated gold sol particles, which may agglutinate in the presence of rubella haemagglutinin antigen. The agglutination which gives a decrease in optical density can be inhibited by specific antibodies present in sera incubated with the immunochemical reagents. The test is performed in microtitration plates and results can be read in a plate-reader. Clinical validation studies were performed comparing the anti-rubella SPIA with the haemagglutination inhibition test and with the latex agglutination test. The sensitivity of the SPIA was calculated to be 99%; the specificity of the test was at least 99.5%. The anti-rubella SPIA is highly suitable for large-scale screening to determine the rubella immune-status.

Clinical validation of an antibody-capture anti-rubella IgM-ELISA.

An antibody-capture IgM-ELISA using monoclonal antibodies for conjugate was subjected to clinical validation with respect to sensitivity and specificity. In 103 serum specimens, known to contain anti-rubella IgM by a sucrose density gradient method, IgM was found by the ELISA in 99 sera. In a second study, 16 out of 17 acute rubella infections were detected by the IgM-ELISA. In 17 out of 17 vaccinees, a specific IgM response could be demonstrated. Specificity of the antibody-capture ELISA was found to be high; no interference was seen in 60 rheumatoid-factor positive sera, in 100 highly positive IgG sera or 10 sera with anti-CMV IgM. Only one out of 100 sera with heterophile antibodies showed a positive response. In acute rubella infections, IgM was shown to be detectable from 1 to 4 days after onset of illness up to about 12 wk, with peak values at about 1 wk after onset.

A novel assay for the quantitative determination of lipoprotein-X (LP-X) in serum.

A new, fast and simple quantitative LP-X assay is described. The method selectively removes apoB-containing lipoproteins by precipitation with specific antibodies. To the supernatant, a precipitation system for LP-X, viz. SDS and MgCl2 in final concentrations of 0.5 g/l and 0.2 mol/l respectively, is added and the turbidity measured at 360 nm. The assay is linear from 0.2 g/l-5.0 g/l and shows a high precision (inter-assay CV of less than 3%). The test correlates favourably with other quantitative LP-X assays, but has the particular advantage that it can be automated and that the time required for one series is only 2 h.

A simple and efficient method for raising steroid antibodies in rabbits.

The production of estradiol antibodies by two immunization procedures was monitored by means of an enzyme-immunoassay. Procedure A consisted of three intramuscular injections given at two-week intervals, followed by five intravenous booster injections and procedure B consisted of multiple intradermal injections given once. Procedure A gave much higher antibody titer. In both procedures the sensitivities of assays using the antisera increased initially and reached a plateau after three to four months of immunization. Consistent changes in specificities were observed. A shortened procedure A is proposed as a simple and efficient procedure for raising steroid antibodies in rabbits.

Diagnosis of fetal rubella infection by nucleic acid hybridization.

The efficacy of nucleic acid hybridization for the diagnosis of rubella infection in experimental and clinical materials was compared with immunoblot and virus isolation techniques. Our results showed that nucleic acid hybridization is specific and rapid but gives false-negative results when compared with conventional virus isolation in some experimental although not in clinical materials so far examined. For this reason, a failure to demonstrate rubella virus in fetal specimens by this method alone cannot yet be taken as a sole criterion for ruling out fetal rubella infection.