Association and linkage of allelic variants of the dopamine transporter gene in ADHD

Previously, we had reported a genome-wide scan for attention-deficit/hyperactivity disorder (ADHD) in 102 families with affected sibs of German ancestry; the highest multipoint LOD score of 4.75 was obtained on chromosome 5p13 (parametric HLOD analysis under a dominant model) near the dopamine transporter gene (DAT1). We genotyped 30 single nucleotide polymorphisms (SNPs) in this candidate gene and its 5' region in 329 families (including the 102 initial families) with 523 affected offspring. We found that (1) SNP rs463379 was significantly associated with ADHD upon correction for multiple testing (P=0.0046); (2) the global P-value for association of haplotypes was significant for block two upon correction for all (n=3) tested blocks (P=0.0048); (3) within block two we detected a nominal P=0.000034 for one specific marker combination. This CGC haplotype showed relative risks of 1.95 and 2.43 for heterozygous and homozygous carriers, respectively; and (4) finally, our linkage data and the genotype-IBD sharing test (GIST) suggest that genetic variation at the DAT1 locus explains our linkage peak and that rs463379 (P<0.05) is the only SNP of the above haplotype that contributed to the linkage signal. In sum, we have accumulated evidence that genetic variation at the DAT1 locus underlies our ADHD linkage peak on chromosome 5; additionally solid association for a single SNP and a haplotype were shown. Future studies are required to assess if variation at this locus also explains other positive linkage results obtained for chromosome 5p.

Attentional functions in children and adolescents with attention-deficit/hyperactivity disorder with and without comorbid tic disorder

Although the coexistence of attention-deficit/hyperactivity disorder (ADHD) and tic disorder (TD) is common, the nature of association is yet not fully understood. Thus, the aim of the present study was to explore attentional dysfunction in children with pure ADHD compared to children with comorbid ADHD + TD. Three groups of 20 children each, aged 8-15 years with either ADHD, ADHD + chronic tic disorder or Tourette syndrome (ADHD + TD) and a healthy control group were compared in their performance on three computerized attention tasks. Tasks of sustained attention, selective attention and interference control were employed. In addition, parental ratings of ADHD symptom severity and behaviour problems were obtained. Both clinical groups were rated as equally inattentive, however, externalising symptoms were more severe in the ADHD group. Objective measures of attentional performance revealed differences between the groups: whereas the ADHD group was markedly impaired in sustaining attention and selective attention/inhibitory control, the ADHD + TD group only showed marginal deficits in selective attention/inhibitory control. Possible explanations for the superior performance of the comorbid group are discussed: In particular, the results may indicate that in some patients, the tic disorder produces behavioural symptoms of ADHD, but not the broad neurocognitive deficits that usually are associated with ADHD. Alternatively, compensatory neural mechanisms of TD patients may result in a better neuropsychological performance of comorbid patients relative to patients suffering from pure ADHD.

Long-term behavior and quality of life after corrective cardiac surgery in infancy for tetralogy of Fallot or ventricular septal defect

The objective of this study was to evaluate behavior and quality of life in children after corrective cardiac surgery in infancy. Twenty cyanotic (tetralogy of Fallot) and 20 acyanotic children (ventricular septal defect), operated at a mean age of 0.7 years with deep hypothermic circulatory arrest (DHCA) and low-flow cardiopulmonary bypass (CPB), were assessed at a mean age of 7.4 years by the Child Behavior Checklist (CBCL) and the German KINDL. Test results were related to perioperative and neurodevelopmental outcome. Compared to healthy children and not significantly different between the groups, internalizing and externalizing problems were elevated, school performance and total competence were reduced, and self- and parent-reported quality of life was not reduced. Parent-reported problems and reduced physical status were correlated with longer durations of DHCA and CPB. Internalizing and externalizing problems, reduced school competence, and reduced self-esteem were associated with reduced endurance capacity. Externalizing problems were related to reduced gross motor function. Poor school competence was related to reduced intelligence and academic achievement. Children with preoperative hypoxemia in infancy due to cyanotic cardiac defects are not at significantly higher risk for behavioral problems and reduced quality of life than those with acyanotic heart defects. The risk of long-term psychosocial maladjustment after corrective surgery in infancy is increased compared to that for normal children and related to the presence of neurodevelopmental dysfunction.

No evidence for preferential transmission of common valine allele of the Val66Met polymorphism of the brain-derived neurotrophic factor gene (BDNF) in ADHD

Attention deficit/hyperactivity disorder (ADHD) is a highly heritable common neurodevelopmental disorder with onset in childhood. A coding SNP (rs6265, Val66Met) of the brain-derived neurotrophic factor gene (BDNF) has recently been associated with ADHD. More specifically, paternal over-transmission of the common Val66 allele to affected children had been observed. We aimed to confirm these findings in a large, sufficiently powered, and well characterized German ADHD family sample. The Val66Met polymorphism of BDNF was genotyped in 294 families comprising one or more affected sibs (468 children). Contrary to previous reports, we did not observe over-transmission of the common Val66 allele, from either parent to affected children. We did not find support for an involvement of the Val66 allele of the Val66Met polymorphism of BDNF in the pathogenesis of ADHD in our sample.

Family-based association study of serotonergic candidate genes and attention-deficit/hyperactivity disorder in a German sample

Alterations in the serotonergic pathway have been implicated in the pathogenesis of attention-deficit/hyperactivity disorder (ADHD). The aim of this study was to investigate seven genetic variants in three genes (serotonin transporter (5-HTT), serotonin receptor 1B (5-HTR1B) and serotonin receptor 2A (5-HTR2A)), which have previously been shown to be associated with ADHD. The polymorphisms under investigation were the 5-HTTLPR, the VNTR in intron 2 and the 3'UTR SNP in 5-HTT, the 5-HTR1B variations 861G>C and 102T>C, and the 5-HTR2A variations His452Tyr and 1438G>A. We genotyped these variants in a sample of 102 families with 229 children with ADHD according to DSM-IV criteria. Among the affected children, 69% fulfilled criteria for the combined type, 27% for the predominantly inattentive type, and 4% for the predominantly hyperactive-impulsive type. Associations were tested by the pedigree transmission disequilibrium test (PDT). All investigated polymorphisms in serotonergic candidate genes showed no association to ADHD in our sample. Earlier studies of these polymorphisms had also shown inconsistent results, with some studies reporting significant associations and others demonstrating no association. This discordance between studies may reflect variation in patient ascertainment criteria, genetic heterogeneity, too low statistical power for the expected effects or false positive results in the initial reports. We cannot rule out the possibility that other variations in the investigated genes contribute to the etiology of ADHD.

A genome-wide scan for attention-deficit/hyperactivity disorder in 155 German sib-pairs

Three groups have previously performed genome scans in attention-deficit/hyperactivity disorder (ADHD); linkage to chromosome 5p13 was detected in all of the respective studies. In the current study, we performed a whole-genome scan with 102 German families with two or more offspring who currently fulfilled the diagnostic criteria for ADHD. Including subsequent fine mapping on chromosome 5p, a total of 523 markers were genotyped. The highest nonparametric multipoint LOD score of 2.59 (empirical genome-wide significance 0.1) was obtained for chromosome 5p at 17 cM (according to the Marshfield map). Subsequent analyses revealed (a) a higher LOD score of 3.37 at 39 cM for a quantitative severity score based on symptoms of inattention than for hyperactivity/impulsivity (LOD score of 1.11 at 59 cM), and (b) an HLOD of 4.75 (empirical genome-wide significance 0.001) based on a parametric model assuming dominant inheritance. The locus of the solute carrier 6A3 (SLC6A3; dopamine transporter 1; DAT1) localizes to 5p15.33; the gene has repeatedly been implicated in the etiology of ADHD. However, in our sample the DAT1 VNTR did not show association with ADHD. We additionally identified nominal evidence for linkage to chromosomes 6q, 7p, 9q, 11 q, 12q and 17p, which had also been identified in previous scans. Despite differences in ethnicity, ascertainment and phenotyping schemes, linkage results in ADHD appear remarkably consistent.

Transmission disequilibrium of polymorphic variants in the tryptophan hydroxylase-2 gene in attention-deficit/hyperactivity disorder

Attention-deficit/hyperactivity disorder (ADHD) is the most common behavioral disorder in childhood with substantial heritability. Pharmacological and molecular genetic studies as well as characterization of animal models have implicated serotonergic dysfunction in the pathophysiology of ADHD. Here, we investigated the effect of polymorphic variants in the gene of the tryptophan hydroxylase-2 (TPH2), the rate-limiting enzyme of serotonin (5-HT) synthesis in the brain, in children and adolescents with ADHD. We analyzed three single nucleotide polymorphisms (SNPs) in and downstream of the transcriptional control region of the TPH2 gene in 103 families with 225 affected children. Allelic association in families with more than one affected child was assessed using the pedigree disequilibrium test. Preferential transmissions were detected for the two SNPs in TPH2's regulatory region (rs4570625, P=0.049; rs11178997, P=0.034), but not for the third SNP in intron 2 (rs4565946, P=0.3517). Haplotype analysis revealed a strong trend of association between the regulatory region SNPs (rs4570625, rs11178997) and ADHD (P=0.064). Our results link potentially functional TPH2 variations to the pathophysiology of ADHD, and further support the relevance of 5-HT in disorders related to altered motor activity and cognitive processes.

Oculomotor inhibition in children with and without attention-deficit hyperactivity disorder (ADHD)

The aim of the present study was to distinguish between a general deficit in oculomotor control and a deficit restricted to inhibitory functions in children with attention deficit hyperactivity disorder (ADHD). In addition, we were interested in differentiating between a general inhibition deficit and deficient subfunctions of inhibition. We used a prosaccade task to measure general oculomotor abilities in 22 children with ADHD and in age- and gender-matched healthy controls. A fixation, an antisaccade and a countermanding saccade task were used to measure specific aspects of oculomotor inhibition. Two major results were obtained: First, our prosaccade task suggests similar saccadic response preparation and saccadic accuracy in the ADHD compared to the control children. Secondly, the fixation and the countermanding saccade task indicate deficits on measures of oculomotor inhibition in the ADHD group. While patients were specifically impaired in stopping an already initiated response or in suppressing exploratory saccades in a novel situation, inhibition of a prepotent response was not deficient. Our data thus indicate an underlying impairment in cognitive inhibition in ADHD that has been associated with prefrontal lobe functions. More specifically, as the anterior cingulate gyrus has been associated with the countermanding saccade task and group differences were most pronounced in this paradigm our data are in line with imaging data stressing the importance of this cortical structure in the pathophysiology of ADHD.

A retrospective study of SSRI treatment in adolescent anorexia nervosa: insufficient evidence for efficacy

Although selective-serotonin-reuptake-inhibitors (SSRI) have been of limited efficacy in the treatment of eating disorder psychopathology and comorbid symptoms of malnourished patients with anorexia nervosa (AN), there is recent data suggesting that SSRI may play a role in preventing relapse among weight-restored patients. Though some previous studies included patients in late adolescence, the vast majority of investigated subjects have been adults. The aim of our retrospective study was to assess the effects of SSRI treatment in partially weight-restored children and adolescents with AN. Thirty two females with AN (mean 14.5+/-1.4 years) were investigated three times during inpatient treatment and at 3- and 6-month follow-up for BMI, eating disorder psychopathology, depressive symptomology, and obsessive-compulsive symptomology. Medication history during inpatient and outpatient treatment was reconstructed at the 6-month follow-up. Nineteen patients received SSRI treatment, while 13 subjects were non-medicated. In comparison to the non-SSRI group, the SSRI group had similar BMI and obsessive-compulsive scores, but higher levels of core eating disorder psychopathology and depressive symptoms at the start of medication. Rates of re-admissions were similar in both groups (SSRI group: 36%, non-SSRI group: 31%, Phi: p=0.72). Repeated measures ANOVA revealed no significant group with time interactions for BMI-SDS (p=0.84), core eating disorder symptoms (ANIS, p=0.79), depression (DIKJ, p=0.75), and obsessive-compulsive (CY-BOCS, p=0.40) scores indicating minimal or no effects of SSRI medication on the course of these variables. In conclusion, our results challenge the efficacy of SSRI medication in the treatment of eating disorder psychopathology as well as depressive and obsessive-compulsive comorbidity in adolescent AN. Clinicians should be chary in prescribing SSRI in adolescent AN unless randomized controlled trials have proofed the benefit of these drugs.

Molecular genetic aspects of attention-deficit/hyperactivity disorder

Two genome wide scans, one of which was subsequently extended, have led to the identification of different chromosomal regions assumed to harbour genes underlying attention-deficit/hyperactivity disorder (ADHD). Some of these regions were also identified in patients with autism and/or dyslexia. The only region for which both studies detected a LOD score >1 was on chr 5p13 which is in the vicinity of the location of the candidate gene DAT1. The candidate gene approach has revealed the most robust and replicated findings for DRD4, DRD5, and DAT1 polymorphisms. Meanwhile interesting endophenotype studies have also been conducted suggesting a genetic basis for different diagnostic and therapeutic criteria. Animal studies for ADHD have investigated especially hyperactivity and have focused mainly on knockout and QTL designs. In knockout mice models the most promising results were obtained for genes of the dopaminergic pathway. QTL results in rodents suggest multiple loci underlying different forms of natural and induced hyperactivity. The molecular results mentioned above are presented and discussed in detail, thus providing both clinicians and geneticists with an overview of the current research status of this important child and adolescent psychiatric disorder.

Mutation screen of the brain derived neurotrophic factor gene (BDNF): identification of several genetic variants and association studies in patients with obesity, eating disorders, and attention-deficit/hyperactivity disorder

Several lines of evidence indicate an involvement of brain derived neurotrophic factor (BDNF) in body weight regulation and activity: heterozygous Bdnf knockout mice (Bdnf(+/-)) are hyperphagic, obese, and hyperactive; furthermore, central infusion of BDNF leads to severe, dose-dependent appetite suppression and weight loss in rats. We searched for the role of BDNF variants in obesity, eating disorders, and attention-deficit/hyperactivity disorder (ADHD). A mutation screen (SSCP and DHPLC) of the translated region of BDNF in 183 extremely obese children and adolescents and 187 underweight students was performed. Additionally, we genotyped two common polymorphisms (rs6265: p.V66M; c.-46C > T) in 118 patients with anorexia nervosa, 80 patients with bulimia nervosa, 88 patients with ADHD, and 96 normal weight controls. Three rare variants (c.5C > T: p.T2I; c.273G > A; c.*137A > G) and the known polymorphism (p.V66M) were identified. A role of the I2 allele in the etiology of obesity cannot be excluded. We found no association between p.V66M or the additionally genotyped variant c.-46C > T and obesity, ADHD or eating disorders. This article contains supplementary material, which may be viewed at the American Journal of Medical Genetics website at http://www.interscience.wiley.com/jpages/0148-7299:1/suppmat/index.html.

Temozolomide and interferon alpha 2b in metastatic melanoma stage IV

BACKGROUND

A multicentre, centrally randomized, open-labelled study with temozolomide and interferon (IFN)-alpha 2b was carried out to study the therapeutic effect in patients with metastatic melanoma stage IV.

OBJECTIVES

The response rate, efficacy, side-effects, reasons for discontinuation of therapy and survival rate of 47 patients treated with temozolomide in combination with two different dosing regimens of IFN-alpha 2b were documented.

PATIENTS/METHODS

Twenty-nine male and 18 female patients (mean age 57.6 years, range 34-74) were centrally randomized to two different arms: 20 patients received a treatment schedule with temozolomide 150 mg m(-2) on days 1-5 orally every 28 days in combination with IFN-alpha 2b 10 MIU m(-2) every other day and 27 patients received temozolomide 150 mg m(-2) on days 1-5 every 28 days in combination with IFN-alpha 2b in a fixed dose of 10 MIU every other day.

RESULTS

We observed an overall response rate of 27.6% comprising five complete remissions (10.6%: one patient group A, four patients group B), in two of these five patients at the last follow-up in the study (4.3%, both in group B); and eight partial remissions (17%: six patients in group A, two patients in group B), in three of these eight patients at the last follow-up in the study (6.4%, two patients in group A, one patient in group B). Three patients showed stable disease (6.4%: one patient in group A, two patients in group B). Mean survival was 14.5 months [95% confidence interval (CI) 10-19] with no significant differences between treatment groups. However, there was a significant correlation with response after three cycles (log rank test, P < 0.03). Within the 32 patients who completed at least three cycles of therapy, seven patients (three in group A and four in group B) with a partial or complete response showed a significantly better mean survival of 30.6 months (95% CI 19.1-42) compared with 25 patients who did not respond (13.7 months 95% CI 9.2-18.3). In total, patients with at least one complete remission showed the longest survival (37.1 months 95% CI 26.3-47.9), followed by patients with at least one partial response (17.4 95% CI 10.9-23.9). Major side-effects of the treatment were nausea, vomiting, headache, leucopenia, thrombopenia, elevation of liver function parameters and neurological symptoms. In five patients, the side-effects led to a discontinuation of treatment: neurological symptoms (two patients), sepsis (one patient), brain haemorrhage (one patient) and exanthema (one patient). There were no treatment-related deaths.

CONCLUSIONS

The combination of temozolomide and IFN-alpha 2b can easily be administered and shows tolerable toxicity. When an objective response occurs after three cycles, it indicates a significant survival advantage.

Verbal memory and aspects of attentional control in children and adolescents with anxiety disorders or depressive disorders

BACKGROUND

The aim was to examine basic performance on attention and memory tasks in treatment-naive children and adolescents with anxiety disorder or depressive disorder and in healthy subjects under drug-free conditions.

METHODS

Basic neurocognitive performance on attention and verbal memory tasks was examined in children and adolescents with emotional disorders, between 6 and 17 years of age. A total of 34 children with an anxiety disorder, 31 children with a depressive disorder, and 33 healthy controls were assessed with a comprehensive neuropsychological test battery. All children were treatment-naive at the time of testing. Five different computerised attention tasks and the Rey Auditory-Verbal Learning Test were administered.

RESULTS

A significant effect of diagnosis was found for verbal memory but not for attention.

LIMITATIONS

The large age range and inclusion of different diagnoses resulted in rather inhomogeneous groups.

CONCLUSION

The present study provided evidence for an undisturbed attentional performance in both patient groups and a dissociation in memory functioning between anxious and depressed children. Memory impairment was found to be specifically associated with childhood depression.

Overweight and obesity in children with Attention-Deficit/Hyperactivity Disorder

OBJECTIVE

Epidemiological studies suggest that adiposity in children may be associated with a reduced level of physical activity. Children with Attention-Deficit/Hyperactivity Disorder (ADHD) are physically hyperactive as of early childhood and have been shown to exhibit higher levels of motor activity than normal. The aim of our study was to assess if the prevalence of overweight and obesity is lower in a population of boys with ADHD in comparison with the German healthy male reference population of the same age.

DESIGN

Patients were investigated from 1999 until 2001 upon referral to the inpatient and outpatient unit of the Department of Child and Adolescent Psychiatry of the University of Aachen.

SUBJECTS

A total of 97 male patients (mean age 10+/-2 y) with a diagnosis of ADHD according the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), who were free of potentially orexigenic medication and who had no further comorbid diagnosis apart from conduct disorder.

MEASUREMENTS

BMI standard deviation scores (BMI-SDS) were calculated and compared to age-adapted reference value of the German population.

RESULTS

Patients' mean BMI-SDS was significantly higher than the age-adapted reference values of the German population (P=0.038). Our sample included significantly more subjects than expected with a BMI > or =90th percentile (19.6%, P<0.001) and > or =97th percentile (7.2%, P=0.007).

CONCLUSION

Surprisingly, being 'hyperactive' in the sense of the DSM-IV diagnosis of ADHD does not prevent the development or persistence of overweight and obesity in children. The examination of these children might be a helpful approach in the investigation of the relationship between obesity and its contributing psychological and behavioural factors.

Age-dependent neuropsychological deficits and effects of methylphenidate in children with attention-deficit/hyperactivity disorder: a comparison of pre- and grade-school children

OBJECTIVE

Pre-school and grade-school children diagnosed with attention-deficit/hyperactivity disorder (ADHD) were compared in their performance on computerized attention tasks. Depending on the nature of the specified attention deficit, subjects were assigned to groups of cognitive subtypes. The effects of methylphenidate (MPH) were analysed depending on age and cognitive subtype.

METHOD

The preschool group comprised 45 children aged 5-7 years; the grade-school group comprised 54 children aged 8-12 years. Children were tested on placebo and on MPH (mean dose: 0.25-0.3 mg/kg body weight) employing tasks of alertness, sustained attention, focused attention, divided attention, and a cognitive conflict task.

RESULTS

Both groups showed measurable attention deficits. While preschoolers were especially impaired in supervisory attention functions, grade-schoolers most frequently exhibited deficits in attention intensity and selectivity. Positive MPH effects were documented for sustained attention in both age-groups. Analysis of MPH effects in dependence on the type of attention impairment (supervisory functions vs. attention intensity/selectivity) revealed a positive relation between deficits in a specific attention domain and MPH effects.

CONCLUSIONS

Age-dependent differences in attention dysfunctions might be due to brain maturational processes. Performance on computerized attention tasks was particularly improved by MPH in children with objectified attention deficits suggesting that neuropsychological diagnostics can be useful to optimise treatment outcome.

[Formal genetic findings in attention-deficit/hyperactivity-disorder]

Twin, family and adoption studies have led to a solid understanding of the contribution of both genetic and environmental factors to the development of attention deficit/hyperactivity disorder (ADHD). We review recent studies under consideration of both methodological aspects and relevant findings. Heritability estimates in the range of 0.6 - 0.8 surpass those for most other child and adolescent psychiatric disorders. First degree relatives have elevated rates for ADHD, affective disorders, conduct disorders and substance abuse and dependency. The ADHD subtype of the index patient does not predict the subtype of other family members affected with ADHD; hence non-genetic factors seemingly account for this intrafamilial variability. Because the familial rates for ADHD are not higher in families of female in comparison to male index patients, there is no indication that the genetic loading is higher in affected females. Recently, rater effects have been discussed broadly: Whereas the heritability estimates are uniformly high independent of the informant (mother, father, teacher), the correlations between quantitatively rated symptoms are low between different informants. Knowledge of the formal genetic aspects of ADHD is a prerequisite for understanding the results of recent molecular genetic studies.

Long term behavioural outcome after neonatal arterial switch operation for transposition of the great arteries

AIMS

To evaluate behavioural outcome and quality of life in children aged 8-14 years after neonatal arterial switch operation for transposition of the great arteries.

METHODS

Sixty children operated as neonates with combined deep hypothermic circulatory arrest and low flow cardiopulmonary bypass were evaluated at age 7.9-14.3 years by the Child Behaviour Checklist (CBCL) and the Inventory for the Assessment of the Quality of Life in Children and Adolescents (IQCL).

RESULTS

Parent reported behavioural outcome on all CBCL problem and competence scores was worse, whereas quality of life on self reported IQCL scores was not reduced compared to the normal population. On multivariate analysis, severe preoperative hypoxia was related to parent reported social problems; peri- and postoperative cardiocirculatory insufficiency was associated with internalizing, externalizing, attention, and total behavioural problems. Reduced expressive language was associated with total behavioural problems, and poor academic achievement was related to parent reported deficits in school performance. Impaired neurological status and reduced endurance capacity both predicted self reported stress by illness.

CONCLUSIONS

The neonatal arterial switch operation with combined circulatory arrest and low flow bypass is associated with parent reported long term behavioural impairment, but not with self reported general reduction in quality of life. This discrepancy may be a result of different perception of illness. In our experience, increased risk of long term psychosocial maladjustment after neonatal corrective cardiac surgery is related to the presence of neurological impairment and reduced endurance capacity.

Lack of inhibition: a motivational deficit in children with attention deficit/hyperactivity disorder and children with traumatic brain injury

Recent research has demonstrated that both brain-injured children and children with attention deficit/hyperactivity disorder (ADHD) suffer from response inhibition deficits. To investigate whether these deficits can be influenced by motivational factors, the stop-signal task was performed with and without reward contingencies for successful inhibition. Three groups of children between 8 and 12 years of age, participated in the study: 31 children with ADHD, 37 with traumatic brain injuries (TBI), and 26 normal controls. Results indicated that, although all groups showed comparable learning effects, reward contingencies had different effects on the groups. Whereas the performance of children with ADHD under reward contingencies were brought up to the performance level of normal controls, rewards were found less effective at improving response inhibition in children with TBI. The results further support a motivational/energetic explanation of the inhibitory deficit in children with ADHD, and of a primary response inhibition deficit due to structural brain damage in children with TBI.

Early development of the müllerian duct in avian embryos with reference to the human. An ultrastructural and immunohistochemical study

In vertebrates, the female reproductive system arises from the Müllerian (paramesonephric) duct which develops in both sexes under the influence of the Wolffian (mesonephric) duct. For a better understanding of the interactions between the Müllerian duct and its adjacent tissues, we present a systematic scanning and transmission electron microscopic investigation of early stages of avian Müllerian duct development. This starts within the cranial part of the Müllerian ridge from a placode-like thickening and deepening of the coelomic epithelium containing nephrostomes as remnants of the last pronephric and first mesonephric tubules. Groups of cells detach from this placode and rapidly expand caudally as a solid cord. This becomes canalized, but the tip region remains mesenchymal and is found enclosed within the basal lamina of the Wolffian duct. Immunostaining reveals that the Müllerian duct migrates within a matrix rich in laminin and entactin. When the canalized duct has opened into the coelomic cavity, one or more secondary ducts are found immediately caudal of the main funnel, for a short period only, possibly to supply material to the expanding duct. BrdU-anti-BrdU reaction reveals a high proliferation of the duct epithelium. The thickened epithelium of the Müllerian ridge dissolves to form the mesenchymal layers of the duct. Immunostaining with vimentin argues against a cellular contribution of Wolffian duct cells to the Müllerian duct. Comparing the data from avian embryos with those of human indicates that the modalities of early Müllerian duct development are similar in both species.

Inhibitory control in children with traumatic brain injury (TBI) and children with attention deficit/hyperactivity disorder (ADHD)

The behavioural and cognitive sequelae of traumatic brain injury (TBI) have features in common with attention deficit/hyperactivity disorder (ADHD), best characterized by deficits in response inhibition.The performance was, therefore, examined of 27 children with TBI, 31 children with developmental ADHD, and 26 matched controls aged 8-12, on two inhibition tasks: the Stop-Signal Task and a Delayed-Response-Task. Children with TBI and children with ADHD showed a pervasive deficit in their inhibitory control processes with respect to inhibition of both pre-potent and on-going responses. In addition, children with TBI were found to suffer from a general slowing of their information processing, which was not correlated with the inhibition deficit. TBI children with and without a secondary ADHD differed only tendentially in their Mean Go-Reaction time in the stop-task. However, subdividing TBI children according to actigraph data into hypo-, hyper- and normokinetic subgroups revealed that the hyperactive TBI children had inhibitory deficit patterns that were similar to children with developmental ADHD. It is concluded that slowing of information processing speed seems to be a general consequence of TBI in childhood, whereas slowing of the stop-processes or inhibitory deficits, specifically, are associated with post-injury hypo- or hyperactivity.

Microarrays: biotechnology's discovery platform for functional genomics

Advances in microarray technology enable massive parallel mining of biological data, with biological chips providing hybridization-based expression monitoring, polymorphism detection and genotyping on a genomic scale. Microarrays containing sequences representative of all human genes may soon permit the expression analysis of the entire human genome in a single reaction. These 'genome chips' will provide unprecedented access to key areas of human health, including disease prognosis and diagnosis, drug discovery, toxicology, aging, and mental illness. Microarray technology is rapidly becoming a central platform for functional genomics.

A dose related response of 6-OHDA on chicken spectral sensitivity and oscillatory potentials of recording electroretinograms

OBJECTIVE

To further study the contribution of dopamine system to the local growth controlling mechanisms, a dose related response of 6-hydroxydopamine (6-OHDA) was studied by recording electroretinograms (ERGs).

METHODS

The spectral sensitivity of the b-waves and spectral efficiency function of oscillatory potentials (OPs) including OP1, OP2 and OP3 in 4 different doses group were measured. The effect of ascorbate that must be contained in solution of 6-OHDA was first tested with the spectral sensitivity of the b-waves and a correlation between response of the OPs and age, as well as a difference in both own eyes was analyzed for determining an intra-subject and inter-subject variance.

RESULTS

An enhanced response was found in OP1, OP2 with doses of 175 micrograms and OP3 with dose of 150 micrograms, and the effect of OPs was mainly in wavelength from 620 nm to 480 nm. No significant increase was found in the spectral sensitivity of the b-waves. The dose 200 micrograms seemed to be toxic to the retina estimated by both spectral sensitivity of the b-waves and spectral efficiency function of the OPs.

CONCLUSIONS

The dose 175 micrograms and 150 micrograms of 6-OHDA yielded an effect on the chicken retina.

Therapy with pulsed electromagnetic fields in aseptic loosening of total hip protheses: a prospective study

Aseptic loosening is the most common problem of hip arthroplasties, limiting its long term success. We report a study of pulsed electromagnetic field (PEMF) treatment in 24 patients with this complication. At the end of treatment, six months and one year later, pain and hip movements improved significantly with the exception of flexion and extension. There was significant improvement in both isotope scans and ultrasonography, but not in plain X-ray. The decreased pain and improved function suggest that PEMF is effective in improving symptoms of patients with loose hip replacement. No improvement, however, can be expected in patients with severe pain due to gross loosening.