Spectrum of gross deletions and insertions in the RB1 gene in patients with retinoblastoma and association with phenotypic expression.

Quantitative multiplex PCR and genomic real-time PCR were used to complete an RB1 mutation analysis in 57 of 433 and 72 of 262 patients with hereditary and isolated unilateral retinoblastoma, respectively. These patients were selected because in previous analyses, which focused mainly on the identification of point mutations, no RB1 mutation was found. We identified gross deletions and insertions in peripheral blood DNA from 26 of 57 patients (46%) with hereditary retinoblastoma, and in six of 72 patients (8.3%) with isolated unilateral disease. In addition, we identified 32 somatic mutations in tumor DNA from 31 of 72 patients (43%) with isolated unilateral retinoblastoma. Together with our previous results, we found that gross RB1 alterations were present in the peripheral blood DNA from 65 of 433 (15%) and 17 of 262 (6.5%) patients with bilateral or familial and isolated unilateral retinoblastoma, respectively. Including reported gross deletions, an analysis of the frequency of breakpoints per intron length shows higher densities in introns 13, 16, 23, and 24. Genotype-phenotype analyses showed that on the whole, carriers of gross deletions develop fewer retinoblastomas compared to patients who are heterozygous for other types of RB1 null mutations. Specifically, carriers of cytogenetic and submicroscopic whole gene deletions often have unilateral tumors only. By contrast, almost all patients with gross deletions with one breakpoint in RB1 have bilateral retinoblastoma.

EEG gamma-band phase synchronization between posterior and frontal cortex during mental rotation in humans.

The main purpose of the present paper was: (1) to study the phase synchronization pattern in the gamma-band while performing the classical Shepard-Metzler task of mental rotation; (2) to investigate the role of musical training; and (3) to study hemispheric differences in the degree of synchronization during mental rotation. Multivariate electroencephalograph signals from 20 male subjects (ten musicians and ten non-musicians) were recorded while performing the mental rotation task and also at resting condition. Phase synchronization was measured by a recent index, mean phase coherence. It was found that synchronization between frontal cortex and right parietal cortex was significantly increased during mental rotation with respect to rest, whereby musicians showed significantly higher degrees of synchronization than non-musicians. Left hemispheric dominance in the degree of phase synchronization, stronger in the posterior right parietal and occipital regions, was observed in musicians. Right hemispheric dominance was generally observed in non-musicians.

Gender dependent EEG-changes during a mental rotation task.

This study is based on 30 students, 15 females and 15 males. EEG was recorded with 19 electrodes according to the international 10/20 system against averaged signals picked up from both ear lobes. Averaged power spectra and cross-power spectra between all electrode-positions were computed. Data were reduced to five frequency bands (theta, alpha1, alpha2, beta1 and beta2) and finally mean amplitude and coherence were computed. EEG-recordings were made during a mental rotation task (Shepard-figures). The obtained spectral parameters were compared with the corresponding values of a baseline activity with eyes open at rest. The results of statistical evaluations (paired Wilcoxon tests, Wilcoxon tests of independent samples) were presented in error probability maps. In males, local coherence decreased between the posterior left electrodes in the theta-band. In females, a decrease of coherence between the posterior right electrodes were observed in this frequency-band. In contrast to females, males showed an increase of coherence between frontal, central and parietal electrode positions in both hemispheres in the alpha1-band. The increase of local coherence in the beta1-band over the right temporo-parietal sites in the male group was more pronounced than in the female group. Especially in females, interhemispheric coherence increased between the posterior electrodes in the theta-, beta1- and beta2-ranges. This study suggests the involvement of many brain areas during mental rotation. Females show a rather symmetrical allocation of coherence increase in theta, beta1 and beta2.