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Biomedical subjects

R Wachsmuth

Publications and source records attributed to R Wachsmuth.

10 recordsLinked to original sources

Linkage and association analysis of nevus density and the region containing the melanoma gene CDKN2A in UK twins.

Rare mutations in the CDKN2A gene are highly penetrant for melanoma. Density of nevi is under strong genetic control and high density is a potent risk factor for melanoma. We used linkage and association analysis in adolescent twins from the UK to examine the hypothesis that the region containing the CDKN2A gene also contains a quantitative trait locus influencing normal nevus development. Five markers in the CDKN2A region were genotyped in 115 dizygotic twin pairs, and one marker (D9S942) was genotyped in 103 monozygotic twin pairs, all of whom had been phenotyped for nevus density. Linkage analysis showed no evidence of a quantitative trait locus influencing nevus density in this chromosomal region. A model partitioning the variation in phenotype into within- and between-twin pair components showed weak evidence of association between higher nevus density and longer mean length of the two D9S942 alleles (P=0.01). This relation, which was also observed in an earlier Australian twin study, could be because of the linkage disequilibrium between D9S942 and a neighbouring functional locus. Further investigation of this region is warranted in large-scale linkage or association studies.

Adolescent↗

Assessment of brain function in adolescent anorexia nervosa before and after weight gain.

This study assessed brain function in 20 adolescent females with anorexia nervosa (AN) and 20 controls using event-related potentials (ERPs) and a battery of neuropsychological tests. In the AN group, N4 latencies for a nonverbal memory task were significantly longer than for a verbal task, and P3 latencies for the verbal task were significantly longer among anorexics as compared to controls. On the nonverbal task, the AN group failed to show a right > left hemispheric asymmetry for P3 amplitudes which was observed for controls. These group differences for P3 latency and amplitude were particularly pronounced in the central-parietal region of the head. Body Mass Index (BMI) in the anorexic group significantly predicted N4 amplitudes for the verbal task in the left hemisphere and P3 amplitudes for the nonverbal task in the right hemisphere. The two groups did not differ on any of the tests used to assess neuropsychological functioning. Eight nutritionally recovered patients and their matched controls were retested using the same procedures. Anorexics showed larger P3 amplitudes for the verbal as compared to the nonverbal task at follow-up. These findings provide evidence for localized brain dysfunction in anorexia nervosa that only partially normalizes with weight gain.

Adolescent↗

Oppositional disorder in children: a validation study comparing conduct disorder, oppositional disorder and normal control children.

Subjects with oppositional disorder (OD, N = 21) and conduct disorder (CD, N = 22) were compared with normal controls (NC, N = 20) to determine whether OD is a distinct disorder. OD subjects exhibited high rates of associated attention deficit, emotional and learning disorders. Compared with NC, OD subjects had high rates of problems in social relationships and came from families characterized by marital fights, dysfunction, and paternal psychopathology. Compared with CD, OD was less often characterized by undersocialization and separations from fathers and more often characterized by dissatisfaction in the marital relationship. These results suggest that OD is a variant of CD rather than of normality.

Achievement↗

Hyperactivity and parental psychopathology.

The association of child hyperactivity and parental psychopathology was explored by establishing lifetime DSM-III diagnoses and histories of childhood hyperactivity among the parents of boys, aged 7-11 yrs, in five diagnostic groups: attention deficit disorder with hyperactivity (ADDH), conduct disorder (CD), ADDH + CD, emotional disorder (ED) and no disorder (NC). These groups were differentiated by a family history of parental psychopathology or childhood hyperactivity. ADDH + CD, CD and ED groups all had significantly higher rates of parental psychopathology than the ADDH and NC groups, for which rates were similar. Significantly more boys in the ADDH, CD and ADDH + CD groups had family histories of parental childhood hyperactivity than did boys in the ED and NC groups.

Anxiety Disorders↗

Effects of event rate and display time on sustained attention in hyperactive, normal, and control children.

Two experiments were conducted to determine whether hyperactive boys have a unique deficit in sustained attention. Groups with DSM-III diagnoses of attention deficit disorder (ADDH), conduct disorder (CD), ADDH + CD, and learning disorder were compared with normal controls on the Continuous Performance Task. In Experiment 1, stimulus presentation rate (stimulus onset asynchrony, SOA) and display time were varied to manipulate attentional demand, and speed and accuracy of performance were measured. The ADDH group was uniquely affected, with less accurate performance at the fastest and slowest SOA. To distinguish the effects of time on task and SOA, the duration of each SOA condition was held constant in Experiment 2. The poorer performance of the ADDH group at the fastest SOA was no longer evident. This finding indicates that the deficit of sustained attention in boys who have ADDH is associated with a greater susceptibility to refractory effects, which is influenced by practice.

Arousal↗

Attaining and maintaining preparation: a comparison of attention in hyperactive, normal, and disturbed control children.

The hypothesis that hyperactive children have a deficit in sustained attention was investigated. Eighteen children who had attention deficit disorder with hyperactivity (ADDH), aged 7 to 11 years, were compared with children who had conduct disorder (n = 15), mixed conduct disorder and ADDH (n = 26), emotional disorder (n = 18), or learning disability (n = 22), and with normal controls (n = 15). The subjects were tested on three versions of the Continuous Performance Task. Sustained attention was assessed from performance with increasing time on task and from ability to prepare attention in response to a warning. Performance of all subjects deteriorated with increasing time and improved with the opportunity to prepare attention. Hyperactive subjects were not more adversely affected by increasing time, nor did they benefit less than controls from the opportunity to prepare attention. Data reanalysis after rediagnosis according to ICD-9 criteria did not change the results. This study did not confirm the hypothesis that hyperactive children have a unique sustained attention deficit.

Affective Symptoms↗

Maprotiline and seizures.

Maprotiline has been reported to be less likely to cause epileptic seizures than the tricyclic antidepressants. The authors describe two cases in which patients suffered their first epileptic attacks while on therapeutic doses of maprotiline. They recommend that the newer antidepressants, as well as the tricyclics, should not be used with the aliphatic neuroleptics because of a possible additive or synergistic epileptic effect. If patients are to be withdrawn from C.N.S. depressants, then this should be accomplished prior to initiation of antidepressant therapy. Patients who are predisposed to seizures should have lower initial doses of antidepressants.

Adult↗