Eliminating first trimester combined testing: Consequences for early detection of significant fetal anomalies

OBJECTIVE

To determine whether implementation of cell-free DNA (cfDNA) testing for aneuploidy as a first-tier test and subsequent abolition of first trimester combined testing (FCT) affected the first trimester detection (<14 weeks) of certain fetal anomalies.

METHODS

We performed a geographical cohort study in two Fetal Medicine Units between 2011 and 2020, including 705 fetuses with prenatally detected severe brain, abdominal wall and congenital heart defects. Cases were divided into two groups: before (n = 396) and after (n = 309) cfDNA introduction. The primary outcome was the first trimester detection rate (<14 weeks) overall and for non-chromosomal anomalies solely.

RESULTS

Overall, gastroschisis, AVSD and HLHS were detected more often in the first trimester in the before group compared to the after group, respectively 54.5% versus 18.5% (p = 0.004), 45.9% versus 26.9% (p = 0.008) and 30% versus 3.4% (p = 0.005). After exclusion of chromosomal anomalies identifiable through cfDNA testing, the detection of AVSD remained higher in the before group (43.3% vs. 9.5%, p = 0.02), leading to a possible earlier gestation at termination. The termination of pregnancy (TOP) rate did not differ among the groups. In the after group, referrals for suspected anomalies following a dating scan between 11 and 14 weeks significantly increased from 17.4% to 29.1% (p < 0.001).

CONCLUSION

This study underscores the value of a scan dedicated to fetal anatomy in the first trimester as we observed a decline in the early detection of certain fetal anomalies (detectable in the first trimester) subsequent to the abolition of FCT.

Congenital small bowel obstruction: Prenatal detection and outcome

OBJECTIVE

To evaluate and compare the outcome of fetuses and neonates with congenital small bowel obstructions (SBO), evaluate the screening performance of prenatal ultrasound for SBO and identify possible risk factors for adverse outcomes.

METHODS

All cases referred to the Amsterdam University Medical Centers between 2007 and 2021 for a prenatal suspected SBO, supplemented by cases of postnatal diagnosis of SBO, were included. The primary outcome was survival after 24 weeks of gestation until the first year of life.

RESULTS

147 cases of SBO were included with a survival rate of 86.2% (119/138) after 24 weeks of gestation until the first year of age. Additional structural or chromosomal anomalies were found to have an increased risk of adverse outcomes. Intrauterine fetal demise occurred in 10/147 (6.8%) cases and 9/147 (6.1%) cases died during postnatal follow-up. The overall positive predictive value of all prenatally diagnosed cases was 91.5%. Surgical correction was performed in 123/128 (96.0%) of the live-born cases.

CONCLUSIONS

Congenital SBO has an overall favorable prognosis, but the outcome is negatively impacted by the possible presence of additional structural or chromosomal anomalies. Fetal monitoring in the early third trimester should be considered, since all cases of Intrauterine fetal demise occurred between 30 and 35 weeks of gestation.

Variation in esophageal physiology testing in clinical practice: Results from an international survey

BACKGROUND

Advances in clinical measurement of esophageal motility and function have improved the assessment of swallowing disorders and reflux symptoms. Variation in data acquisition, analysis, and reporting exists and impacts on diagnosis and management.

AIMS AND METHODS

This study examined variation in esophageal manometry methodology between institutions to establish the status in current practice. A structured survey was distributed through international NGM societies using an Internet-based platform. Questions explored infrastructure, technology, analysis, and reporting.

KEY RESULTS

Responses were received from 91 centers from 29 countries. Eighteen (20%) centers used "conventional" manometry, 75 (82%) high-resolution manometry, and 53 (58%) HR impedance manometry. All centers documented motility for single water swallows. The Chicago Classification was applied by 65 (71.4%) centers. In contrast, analysis of EGJ morphology varied widely. Adjunctive testing was often applied: multiple rapid swallows (77%), rapid drink challenge (77%), single solid swallows (63%), and a standard test meal (18%). Of 86 (94.5%) units that offered pH impedance (pH-Z) studies, approximately half (53.5%) performed tests on acid-suppressant medication in patients with a high pretest probability (eg, erosive esophagitis). Most (75.6%) centers manually reviewed every reflux event. Others examined pH-Z data only prior to symptoms. To assess symptom association with reflux events, 73.6% centers analyzed each symptom separately, whereas 29.7% centers pooled symptoms.

CONCLUSIONS AND INFERENCES

There is marked variation in the data acquisition, analysis, and reporting of esophageal manometry studies. Further efforts to improve quality and uniformity in testing and reporting are required. This survey provides information upon which best-practice guidelines can be developed.

Cue reactivity towards bodies in anorexia nervosa - common and differential effects in adolescents and adults

BACKGROUND

Aberrant reward mechanisms with regard to slim body shapes are discussed in patients with anorexia nervosa (AN). The aim of the present study was to examine of cue reactivity toward body shapes in AN via the late positive potential (LPP), an event-related electroencephalography (EEG) component. By including adolescents and adults, aspects of development and chronification could be studied (2 × 2 design).

METHODS

Thirty-two female AN patients (19 adolescents and 13 adults) and 37 control participants (16 adolescents and 21 adults) were included. Standardized photographic stimuli showing women's bodies in underwear from five body mass index (BMI) categories (extremely underweight to extremely overweight) were presented. During picture evaluation, EEG activity was recorded (10-20 system). The LPP was measured in two time windows characterized by different topographies (450-700 ms: posterior; 1000-1300 ms: central).

RESULTS

Regarding the posterior component, LPP amplitudes were clearly reduced in adult but not in adolescent patients; for both time windows the LPP showed differential patterns over BMI categories for patients and controls. Regarding the central component, a highly significant linear decrease from extremely underweight to extremely overweight body shapes was revealed in patients and no significant modulation in control participants.

CONCLUSIONS

Adolescent and adult patients show increased sustained attention toward extremely underweight bodies. In chronically ill patients, this bias appears to be accompanied by generally reduced automatic attention. The LPP findings provide a differentiated picture of aberrant cue reactivity which could be interpreted as motivated attention toward body shapes in AN.

Genetic polymorphisms associated with smoking behaviour predict the risk of surgery in patients with Crohn's disease

BACKGROUND

Smoking is a strong environmental factor leading to adverse outcomes in Crohn's disease, but a more benign course in ulcerative colitis. Several single nucleotide polymorphisms (SNPs) are associated with smoking quantity and behaviour.

AIM

To assess whether smoking-associated SNPs interact with smoking to influence the clinical course of inflammatory bowel diseases.

METHODS

Genetic and prospectively obtained clinical data from 1434 Swiss inflammatory bowel disease cohort patients (821 Crohn's disease and 613 ulcerative colitis) were analysed. Six SNPs associated with smoking quantity and behaviour (rs588765, rs1051730, rs1329650, rs4105144, rs6474412 and rs3733829) were combined to form a risk score (range: 0-12) by adding the number of risk alleles. We calculated multivariate models for smoking, risk of surgery, fistula, Crohn's disease location and ulcerative colitis disease extent.

RESULTS

In Crohn's disease patients who smoke, the number of surgeries was associated with the genetic risk score. This translates to a predicted 3.5-fold (95% confidence interval: 2.4- to 5.7-fold, P<.0001) higher number of surgical procedures in smokers with 12 risk alleles than individuals with the lowest risk. Patients with a risk score >7 had a significantly shorter time to first intestinal surgery. The genetic risk score did not predict surgery in ulcerative colitis or occurrence of fistulae in Crohn's disease. SNP rs6265 was associated with ileal disease in Crohn's disease (P<.05) and proctitis in ulcerative colitis (P<.05).

CONCLUSIONS

SNPs associated with smoking quantity is associated with an increased risk for surgery in Crohn's disease patients who smoke. Our data provide an example of genetics interacting with the environment to influence the disease course of inflammatory bowel disease.

Methods of anorectal manometry vary widely in clinical practice: Results from an international survey

BACKGROUND

Ano-rectal manometry (ARM) is the most commonly performed investigation for assessment of anorectal dysfunction. Its use is supported by expert consensus documents and international guidelines. Variation in technology, data acquisition, and analysis affect results and clinical interpretation. This study examined variation in ARM between institutions to establish the status of current practice.

METHODS

A 50-item web-based questionnaire assessing analysis and interpretation of ARM was distributed by the International Anorectal Physiology Working Group via societies representing practitioners that perform ARM. Study methodology and performance characteristics between institutions were compared.

KEY RESULTS

One hundred and seven complete responses were included from 30 countries. Seventy-nine (74%) institutions performed at least two studies per week. Forty-nine centers (47%) applied conventional ARM (≤8 pressure sensors) and 57 (53%) high-resolution ARM (HR-ARM). Specialist centers were most likely to use HR-ARM compared to regional hospitals and office-based practice (63% vs 37%). Most conventional ARM systems used water-perfused technology (34/49); solid-state hardware was more frequently used in centers performing HR-ARM (44/57). All centers evaluated rest and squeeze. There was marked variation in the methods used to report results of maneuvers. No two centers had identical protocols for patient preparation, setup, study, and data interpretation, and no center fully complied with published guidelines.

CONCLUSIONS & INFERENCES

There is significant discrepancy in methods for data acquisition, analysis, and interpretation of ARM. This is likely to impact clinical interpretation, transfer of data between institutions, and research collaboration. There is a need for expert international co-operation to standardize ARM.

Prenatal and adult androgen activities in alcohol dependence

OBJECTIVE

Alcohol dependence is more prevalent in men than in women. The evidence for how prenatal and adult androgens influence alcohol dependence is limited. We investigated the effects of prenatal and adult androgen activity on alcohol dependence. Moreover, we studied how the behaviours of pregnant women affect their children's prenatal androgen load.

METHOD

We quantified prenatal androgen markers (e.g., second-to-fourth finger length ratio [2D : 4D]) and blood androgens in 200 early-abstinent alcohol-dependent in-patients and 240 controls (2013-2015, including a 12-month follow-up). We also surveyed 134 women during pregnancy (2005-2007) and measured the 2D : 4D of their children (2013-2016).

RESULTS

The prenatal androgen loads were higher in the male alcohol-dependent patients compared to the controls (lower 2D : 4D, P = 0.004) and correlated positively with the patients' liver transaminase activities (P < 0.001) and alcohol withdrawal severity (P = 0.019). Higher prenatal androgen loads and increasing androgen levels during withdrawal predicted earlier and more frequent 12-month hospital readmission in alcohol-dependent patients (P < 0.005). Moreover, stress levels (P = 0.002), alcohol (P = 0.010) and tobacco consumption (P = 0.017), and lifetime stressors (P = 0.019) of women during pregnancy related positively to their children's prenatal androgen loads (lower 2D : 4D).

CONCLUSION

Androgen activities in alcohol-dependent patients and behaviours of pregnant women represent novel preventive and therapeutic targets of alcohol dependence.

Self-disinfecting surfaces and activity against Staphyloccocus aureus ATCC 6538 under real-life conditions

Environmental surface contamination provides a potential reservoir for pathogens to cause infections. As such, self-disinfecting surfaces have been developed to possibly reduce exogenous transmission. Five different self-disinfecting surfaces were evaluated for activity against Staphylococcus aureus ATCC 6538 under real-life conditions using the dry inoculation method. Various antimicrobial effects were detected. However, following disinfection with alcoholic wipes, these effects disappeared. Further development is necessary to produce self-disinfecting surfaces that are stable in the presence of hospital disinfectants, as it is impossible to guarantee that self-disinfecting surfaces in healthcare settings will not be exposed to disinfectants.

Inter-observer agreement for diagnostic classification of esophageal motility disorders defined in high-resolution manometry

High-resolution esophageal manometry (HRM) is a recent development used in the evaluation of esophageal function. Our aim was to assess the inter-observer agreement for diagnosis of esophageal motility disorders using this technology. Practitioners registered on the HRM Working Group website were invited to review and classify (i) 147 individual water swallows and (ii) 40 diagnostic studies comprising 10 swallows using a drop-down menu that followed the Chicago Classification system. Data were presented using a standardized format with pressure contours without a summary of HRM metrics. The sequence of swallows was fixed for each user but randomized between users to avoid sequence bias. Participants were blinded to other entries. (i) Individual swallows were assessed by 18 practitioners (13 institutions). Consensus agreement (≤ 2/18 dissenters) was present for most cases of normal peristalsis and achalasia but not for cases of peristaltic dysmotility. (ii) Diagnostic studies were assessed by 36 practitioners (28 institutions). Overall inter-observer agreement was 'moderate' (kappa 0.51) being 'substantial' (kappa > 0.7) for achalasia type I/II and no lower than 'fair-moderate' (kappa >0.34) for any diagnosis. Overall agreement was somewhat higher among those that had performed >400 studies (n = 9; kappa 0.55) and 'substantial' among experts involved in development of the Chicago Classification system (n = 4; kappa 0.66). This prospective, randomized, and blinded study reports an acceptable level of inter-observer agreement for HRM diagnoses across the full spectrum of esophageal motility disorders for a large group of clinicians working in a range of medical institutions. Suboptimal agreement for diagnosis of peristaltic motility disorders highlights contribution of objective HRM metrics.

Toward more accurate measurements of anorectal motor and sensory function in routine clinical practice: validation of high-resolution anorectal manometry and Rapid Barostat Bag measurements of rectal function

BACKGROUND

Measurements of anorectal function using high-resolution anorectal manometry (HR-ARM) and rectal barostat technology provide more reliable results than standard ARM with an elastic balloon; however, HR-ARM results have not been compared to ARM and standard barostat protocols are impractical in routine clinical practice. The aim of this study was to validate HR-ARM against standard ARM and standard barostat against a novel Rapid Barostat Bag (RBB) measurement and elastic balloon measurements of rectal function.

METHODS

Twenty-six healthy volunteers (15 female, 11 male, 19-52 years) were studied. Measurements of anal function and simulated defecation were compared for 12-sensor HR-ARM and 6-sensor standard ARM using line plots from the same recording. Rectal capacity, compliance, and sensation (volume threshold) were measured by elastic balloon, standard barostat, and RBB methods using stepwise inflation of a 700-mL polyethylene bag to 40 mmHg distension by electronic barostat and handheld syringe monitored by sphygmo-manometer, respectively. Results are reported as mean ± SD. Bland-Altman plots and correlation coefficients (r) for measurements were calculated.

KEY RESULTS

There was excellent agreement between HR- and standard ARM measurements (r > 0.86, <25 mmHg difference) and between standard barostat and RBB measurements of rectal capacity (r = 0.97, <25 mL difference). Correlation coefficients of threshold volumes for initial perception, urgency and discomfort were 0.37, 0.71, and 0.95, respectively. No significant correlation was present with elastic balloon measurements. Time to complete studies was shorter for HR-ARM than standard ARM and for RBB than standard barostat in historical controls.

CONCLUSIONS & INFERENCES

HR-ARM with RBB measurements of anorectal function provides quick and reasonably accurate measurements of continence function suitable for use in routine clinical practice (ClinicalTrial.gov NCT01456442).

Familiality of neural preparation and response control in childhood attention deficit-hyperactivity disorder

BACKGROUND

Patients with attention deficit-hyperactivity disorder (ADHD) exhibit difficulties in multiple attentional functions. Although high heritability rates suggest a strong genetic impact, aetiological pathways from genes and environmental factors to the ADHD phenotype are not well understood. Tracking the time course of deviant task processing using event-related electrophysiological brain activity should characterize the impact of familiality on the sequence of cognitive functions from preparation to response control in ADHD. Method Preparation and response control were assessed using behavioural and electrophysiological parameters of two versions of a cued continuous performance test with varying attentional load in boys with ADHD combined type (n = 97), their non-affected siblings (n = 27) and control children without a family history of ADHD (n = 43).

RESULTS

Children with ADHD and non-affected siblings showed more variable performance and made more omission errors than controls. The preparatory Cue-P3 and contingent negative variation (CNV) following cues were reduced in both ADHD children and their non-affected siblings compared with controls. The NoGo-P3 was diminished in ADHD compared with controls whilst non-affected siblings were located intermediate but did not differ from both other groups. No clear familiality effects were found for the Go-P3. Better task performance was further associated with higher CNV and P3 amplitudes.

CONCLUSIONS

Impairments in performance and electrophysiological parameters reflecting preparatory processes and to some extend also for inhibitory response control, especially under high attentional load, appeared to be familially driven in ADHD and may thus constitute functionally relevant endophenotypes for the disorder.

The effect of standard compared to enhanced instruction and verbal feedback on anorectal manometry measurements

BACKGROUND

Guidelines recommend instruction and motivation during anorectal manometry; however, its impact on findings has not been reported. This study assessed the effects of standard versus enhanced instruction and verbal feedback on the results of anorectal manometry.

METHODS

High-resolution manometry was performed by a solid-state catheter with 10 circumferential sensors at 6 mm separation across the anal canal and two rectal sensors. Measurements were acquired first with standard instruction and then with enhanced instruction and verbal feedback. On both occasions, squeeze pressure and duration during three voluntary contractions and intra-rectal pressure and recto-anal pressure gradient (RAPG) during three attempts at simulated defecation were assessed.

KEY RESULTS

A total of 70 consecutive patients (54 female; age 25-82 years) referred for investigation of fecal incontinence (n = 31), constipation, and related disorders of defecation (n = 39) were studied. Enhanced instruction and verbal feedback increased maximum squeeze pressure (Δ10 ± 28.5 mmHg; P < 0.0038) and duration of contraction (Δ3 ± 4 s; P < 0.0001). During simulated defecation, it increased intra-rectal pressure (Δ12 ± 14 mmHg; P < 0.003) and RAPG (Δ11 ± 20 mmHg; P < 0.0001). Using standard diagnostic criteria, the intervention changed manometric findings from locally validated 'pathologic' to 'normal' values in 14/31 patients with incontinence and 12/39 with disorders of defecation.

CONCLUSIONS & INFERENCES

Enhanced instruction and verbal feedback significantly improved voluntary anorectal functions and resulted in a clinically relevant change of manometric diagnosis in some patients. Effective explanation of procedures and motivation during manometry is required to ensure consistent results and to provide an accurate representation of patient ability to retain continence and evacuate stool.

[How does maternal alcohol consumption during pregnancy affect the development of attention deficit/hyperactivity syndrome in the child]

Besides genetic susceptibility, environmental factors and gene-environment interactions are of central interest in research on attention deficit/hyperactivity disorder in children. Focusing on maternal behaviour during pregnancy, prenatal maternal alcohol consumption is associated with behavioural disorders in children. In animal models, developmental disorders of brain structures as well as subsequent behavioural disorders - similar to findings in attention deficit disorder - were caused by prenatal alcohol exposure. These findings occur in small rodents (mice, rats) as well as in primates and can be caused by even moderate alcohol exposure. In foetal alcohol syndrome (FAS) and foetal alcohol spectrum disease (FASD) in humans, symptoms like hyperactivity, disruptive or impulsive behaviour along with reduced attention and slower reaction time are observed. These findings resemble the symptoms of ADHD. For that reason, children diagnosed with FAS/FASD are frequently diagnosed with ADHD in parallel. Even small amounts of alcohol during pregnancy are responsible for cognitive and behavioural impairments like a significantly decreased IQ. About 50 % of adult ADHD patients show alcohol abuse or dependency and/or other substance disorders. Due to this, a higher rate of prenatal exposition to psychoactive substances for children of mothers affected with ADHD seems probable. However, there are no sufficient data on ADHD and its association to substance abuse in pregnancy, which makes it difficult to quantify the impact of genetic and environmental causes for the development of childhood ADHD. So far, no link could be proven with a high level of evidence between moderate prenatal alcohol consumption and the development of childhood ADHD. It has to be recognised that all present studies are based on self-reported alcohol consumption. Data collected by this methodology are usually severely biased to an underestimation of alcohol abuse. Objective tests for alcohol abuse in pregnancy, such as the analysis of fatty acid ethyl esters or ethyl glucuronide in foetal feces after birth, show rates of alcohol consumption in pregnant women which are dramatically higher than reported. Therefore, studies investigating the association between prenatal alcohol exposure and ADHD should incorporate the analysis and validation of more objective methods, such as parameters for alcohol degradation.

Measurement of redox potential and steroid concentrations in the follicular fluid of growing and regressing follicles of mares

The aim of this study was to prove if oxidation-reduction levels in the follicular fluid were new functional indices of follicular health and whether there was a high level of accordance with endocrinological parameters and with the growth stage as detected by ultrasound monitoring of individual follicles during the oestrous cycle in mares. Follicles were classified as growing and regressing follicles using ultrasonography. Altogether 48 follicles with a diameter from 20 to 56 mm were aspirated by transvaginal ultrasound guided follicular aspiration. Follicular concentration of oestradiol and progesterone in relation to the diameter of growing follicles showed correlations of r = 0.64 and r = 0.57, respectively. The redox potential derived index D2 varied from -448 to +431 in the collected fluids of the follicles. The accordance of the judgement of all follicles using both complexes of methods - endocrinological and ultrasonographic parameters vs. analysis of oxidation and reduction levels - reached 72.5%. This finding has shown that parameters of redox reactions do not correlate closely with the stage of follicular growth or regression as determined by in vivo scanning of ovaries or by assessment of follicular steroid concentrations. However, the measurement of redox potentials offers an opportunity to examine the whole process of metabolism in follicular cells and to forecast impairments of cellular performances. Changes of redox parameters in growing follicles enable an earlier prediction of their further development. The data demonstrate that growing and regressing follicles do not represent nonatretic, early atretic and atretic follicles, respectively.

Bulk interfaces in a Ni-rich Ni-Au alloy investigated by high-resolution Z-contrast imaging

Interfaces between Au-rich precipitates and the Ni-rich matrix in a decomposed Ni-10 at.% Au alloy were investigated by low-magnification and high-resolution Z-contrast imaging. During aging at 923 K, the originally single crystalline sample decomposed and recrystallized resulting in a microstructure consisting of subgrains separated by small-angle grain boundaries. These small-angle grain boundaries are decorated by Au-rich precipitates. The interfaces between the Au-rich precipitates and the Ni-rich matrix were characterized with respect to the orientation relationship between precipitates and matrix, misfit dislocations and concentration gradients. Two transformation modes were identified that are involved in the decomposition of bulk Ni-rich Ni-Au alloys. While in the first mode the interface is semi-coherent, in the second mode the interface corresponds to an incoherent twin boundary. It is further shown that strain fields around misfit dislocations can result in systematic errors in the determination of the concentration gradients across interfaces between precipitates and matrix.

Questioning inhibitory control as the specific deficit of ADHD ? evidence from brain electrical activity

OBJECTIVE

To investigate motor response control during a cued continuous performance test (CPT-A-X) by performance and ERP parameters in children with hyperkinetic disorder (HD), hyperkinetic conduct disorder (HCD) or oppositional deviant/conduct disorder (ODD/CD), to examine the evidence for an inhibition-specific deficit as indicated by these parameters, and to analyze whether possible deviations are specific for HD/HCD.

METHOD

Behavioral parameters and event-related potentials (ERPs) were recorded during a CPT-A-X-task in children (aged 8 to 14 years) with either HD (n = 15), HCD (n = 16), or ODD/CD (n = 15) and normal children (n = 18) and analysed. ICD-10 diagnoses of HD/HCD diagnoses in all children were fully concordant with the DSM-IV diagnosis of ADHD-combined type.

RESULTS

Children with HCD committed more dyscontrol errors and differed most from normal children on ERP measures of motor response control, while children with HD-only were more impaired during processing of the warning stimuli for motor preparation. ERP measures specific for response inhibition were not different between the groups.

CONCLUSIONS

The results show that ADHD cannot be fully explained by an inhibition-specific deficit and implicate impaired response execution processes as well. This indicates that comorbid children suffer from a reduced ability to control their prepared motor responses. Further, they seem to have difficulties in timely switching attention from monitoring the sensory input stream to the monitoring of own responses and actions.

Methylphenidate enhances both intracortical inhibition and facilitation in healthy adults

Transcranial magnetic stimulation was used to investigate the effect of the psychostimulant drug methylphenidate (MPH) on motor cortex excitability in healthy adults (n = 12) in a placebo-controlled, crossover design study. MPH caused an enhancement of intracortical inhibition as well as intracortical facilitation. Enhancement of both of these TMS parameters was unexpected and suggests that MPH exerts its action on the motor cortex not only through the dopaminergic neurotransmitter system.

Quantitative characterisation of chemical inhomogeneities in Al-Ag using high-resolution Z-contrast STEM

The incoherent imaging model is applied to interpret high-resolution Z-contrast micrographs. A simple method for a column-by-column resolved characterisation of Ag-rich precipitates in Al-Ag is developed. No information on the detailed imaging process is required. Evaluating the high-angle scattering intensities of Al and Ag by image analysis, the number of Ag atoms contained in individual atomic columns can be determined accurately and moreover, the thickness of the thin foil can be calculated. Multislice simulations confirm the broad validity of the incoherent imaging model for Z-contrast STEM and are used to check the method presented. Finally, the image analysis is applied to experimental Z-contrast images of Guinier-Preston zones in Al-3 at% Ag. The Ag content of the individual atomic columns can be determined with an accuracy better than +/-10%.

Methylphenidate and intracortical excitability: opposite effects in healthy subjects and attention-deficit hyperactivity disorder

OBJECTIVE

To test the effects of a standard dosage of the psychostimulant methylphenidate (MPH) - which significantly enhances intracortical inhibition but had no effects on intracortical facilitation in children with attention-deficit hyperactivity disorder (ADHD) - on intracortical excitability in healthy subjects.

METHOD

In 12 healthy subjects, aged 20-40 years, intracortical inhibition and facilitation were investigated before and 70 min after the intake of 10 mg MPH using the technique of transcranial magnetic stimulation (TMS) with the paired-stimulus paradigm.

RESULTS

In comparison of the two TMS measurements, a significant enhancement in intracortical facilitation but no effects on intracortical inhibition could be stated under MPH administration.

CONCLUSION

This study provides first evidence for opposite effects of MPH on intracortical excitability in healthy adult subjects showing enhanced intracortical facilitation in contrast to ADHD children in whom enhanced intracortical inhibition has recently been shown.

[Investigations of humoral and cellular regulation mechanisms of the redox-homeostasis in cattle from ecological farming--2. Influence of race and age on the enzymatic redox control in the blood plasma]

The present study examined the effects of race and age on the redox potential behavior of blood plasma samples. The blood plasma from clinical healthy heifers (44) and calves (45) were investigated. The animals presented three different cattle races (Limousin, Angus and Hereford), grazed on pasture. The blood plasma test consists of two parts: analysis of the initial redoxpotential as well as the investigation of the action of biocatalists. ATP, ATP plus caffeine, GTP and FAD+ were used as an adding substances for the differential analysis. The influence of biocatalist on the redox balance and the reaction of the redox dependent enzymatic system of native plasma significant correlated with animal race and age.

[The redox status of the blood plasma in cattle from ecological farming--1. Influence of genotype and age on the antioxidant defence capacity in the blood plasma]

The present study examined the effects of race and age on the redox potential behavior of blood plasma samples. The oxidative stability was studied in the reaction with p-benzoquinone. The investigated animals represented three different cattle races (Limousin, Angus and Hereford), grazed on pasture. The blood samples from clinical healthy heifers (44) and calves (45) were investigated. The following parameters were determined: the start level of redox potential and the level after adding 10, 20, and 30 mg p-benzoquinone to the samples. The analyses of the redox potentials showed the advantage of oxidative stability of heifers compared with calves. The results showed a significant effect of race on the redox potential behavior of blood plasma.

[Transcranial magnetic stimulation in child and adolescent psychiatry: excitability of the motor system in tic disorders and/or attention deficit hyperactivity disorders]

Motor system excitability can be investigated in vivo by means of single and paired pulse transcranial magnetic stimulation (TMS). Whereas the cortical silent period reflects the general degree of inhibitory mechanisms mainly within the sensorimotor loop, intracortical excitability measures the focused degree of inhibitory and facilitatory mechanisms within the motor cortex. In child and adolescent psychiatric disorders with uncontrollable motor behavior such as tics in tic disorder or motoric hyperactivity in attention deficit hyperactivity disorder (ADHD), different dysfunctional patterns of motor system excitability could be demonstrated compared to age-matched healthy controls: (1) In tic disorder, a shortened cortical silent period was observed, providing evidence of deficient inhibitory mechanisms within the sensorimotor loop, probably primarily at the level of the basal ganglia. (2) In ADHD, a decreased intracortical inhibition was found, probably reflecting deficient inhibitory mechanisms within the motor cortex (but enhancement of intracortical inhibition after oral intake of 10 mg methylphenidate). In order to investigate neurophysiological aspects of comorbidity, (3) motor system excitability was also measured in children with combined ADHD and tic disorder. The findings of a reduced intracortical inhibition as well as a shortened cortical silent period in these comorbid children provide evidence of additive effects at the level of motor system excitability. These decreased inhibitory mechanisms within the entire sensorimotor loop and especially the motor cortex could be essential neurobiological substrates of the deficient inhibitory motor control and regulation, respectively, in tic disorder and ADHD.

Transkranielle Magnetstimulation in der Kinder- und Jugendpsychiatrie: Exzitabilität des motorischen Systems bei Tic-Störungen und/oder Aufmerksamkeitsdefizit-/ Hyperaktivitätsstörungen

Zusammenfassung: Mit der transkraniellen Magnetstimulation (TMS) kann die Exzitabilität des motorischen Systems direkt in vivo untersucht werden. Diese Methode wurde deshalb bei Kindern mit solchen Störungsbildern angewandt, bei denen sich eine unzureichende Steuerung, Kontrolle und/oder Regulation motorischer Abläufe feststellen lässt: Eine “musterbezogene” Überaktivität bei Tic-Störungen, eine “allgemeine” motorische Überaktivität bei Aufmerksamkeitsdefizit-/Hyperaktivitätsstörungen (ADHS). Im Vergleich zu gesunden Kindern waren bei Kindern mit diesen hypermotorischen Störungsbildern unterschiedliche Auffälligkeiten festzustellen: (1) Eine verkürzte Kortikale Silent Period und damit ein Hinweis auf defizitäre inhibitorische Prozesse wahrscheinlich auf Ebene der Basalganglien bei Kindern mit Tic-Störungen (offenbar kein Einfluss klinisch wirksamer Medikamente), (2) eine verminderte intrakortikale Inhibition und damit ein Hinweis auf defizitäre inhibitorische Prozesse eher im Bereich des Motorkortex bei Kindern mit ADHS (Zunahme der intrakortikalen Inhibition unter Methylphenidatgabe). (3) Bei Kindern mit komorbider ADHS und Tic-Störung waren beide neurophysiologischen Veränderungen i.S. eines “additiven” Inhibitionsdefizites im motorischen System aufzeigbar. Mit diesen TMS-Untersuchungen konnten bei Kindern mit den hypermotorischen Störungsbildern Tic-Störungen und ADHS neue Befunde zur Darstellung neurobiologischer Grundlagen (“Inhibitionsdefizite im motorischen System”), zur Frage der Komorbidität (“additiver Effekt im motorischen System”) sowie zum Wirkmechanismus entsprechender Psychopharmaka (“Verbesserung des Inhibitionsvermögens im motorischen System bei ADHS unter Methylphenidat”) erarbeitet werden.

Time-on-task analysis using wavelet networks in an event-related potential study on attention-deficit hyperactivity disorder

OBJECTIVE

The aim of this event-related potential (ERP) study was to test time-on-task analysis at the level of single sweeps in a clinical trial. Since inattentiveness is one of the main symptoms of attention-deficit hyperactivity disorder (ADHD), this child psychiatric disorder was chosen as an exemplary application.

METHODS

Twenty-four healthy and 24 ADHD boys, aged 9--15 years, performed an auditory selective attention task for about 5 min. ERP single trials were analyzed using wavelet networks. Time-on-task analysis was applied to omission errors, reaction time and slow ERP components (frontal negativity, parietal positivity), represented by a low-frequency wavelet component.

RESULTS

Both performance and ERP measures showed distinct temporal dynamics. Time-on-task effects were not only linear, but also of higher order and started after less than 1 min. For ADHD children, earlier time-on-task effects, i.e. an earlier increase of omission errors and frontal negativity, resulted. Healthy children could allocate more attentional resources during the course of the experiment.

CONCLUSION

Time-on-task analysis at the level of single trials revealed phenomena probably reflecting ADHD children's attentional deficits. Thus, a more differentiated ERP analysis may provide a better understanding of the pathophysiological background in neuropsychiatric disorders.

Children with comorbid attention-deficit-hyperactivity disorder and tic disorder: evidence for additive inhibitory deficits within the motor system

For children with attention-deficit-hyperactivity disorder (ADHD) or tic disorder (TD), we recently reported deficient inhibitory mechanisms within the motor system by using transcranial magnetic stimulation. These deficits--stated as reduced intracortical inhibition in ADHD and shortened cortical silent period in TD--could be seen as neurophysiological correlates of motor hyperactivity and tics, respectively. To investigate neurophysiological aspects of comorbidity, we measured motor system excitability for the first time also in children with combined ADHD and TD. The findings of a reduced intracortical inhibition as well as a shortened cortical silent period in these comorbid children provide evidence for additive effects at the level of motor system excitability.