P300 and alpha event-related desynchronization (ERD)

In the present study we evaluated the relationships between the P300 event-related potential and event-related desynchronization (ERD) of electroencephalographic alpha activity by simultaneously analyzing P300 as well as 7-10- and 10-14-Hz alpha ERD responses from auditory passive and active oddball conditions. We compared the effects of task (target vs. nontarget) and electrode (Fz, Cz, Pz) on P300 and ERD, and correlated P300 amplitude/latency with ERD maximal amplitude/latency across individuals. The major findings were that P300 as well as slow and fast alpha ERD manifested similar task and electrode effects. P300 preceded ERD and predicted individual variance of both slow and fast alpha ERD. The relationships of P300 with alpha ERD were different for the slow and fast alpha frequencies. These findings indicate that P300 and ERD are related such that slow and fast alpha ERDs are specifically guided or modified by the internal event(s) indexed by P300.     

Molecular and cellular modulation of fibrinolysis

The structure of the fibrin network, the hemodynamic environment of the clot, the kinetic properties of the fibrinolytic enzymes and the balance of their formation and inactivation essentially determine the effectiveness of fibrinolysis in vivo. The fibrin structure and the action of proteases, however depend considerably on additional, apparently inert physiological and pathological factors, which are restricted to more or less transient compartments in fluid-solid interface, such as thrombus (fibrin with platelet membrane structures), endothelial cell surface, the environment of polymorphonuclear cells (PMN). In these compartments extreme changes in concentrations and rate enhancements are observed. Components released by endothelial cells, PMNs and platelets or molecules present in circulating blood create a heterogeneous milieu that modulates fibrinolysis. This review summarizes the effects, and where it is possible, explains the mechanism of modulators of the fibrinolytic processes, such as cell membrane and cellular contents of endothelium, PMN and platelets present in thrombi, the action of normal and pathological blood plasma- and extracellular matrix-components.     

The human vertical optokinetic afternystagmus and the effect of gravity during pitch tilt

BACKGROUND: Findings concerning human vertical optokinetic afternystagmus (VOKAN) are often not consistent and in some cases even contradictory. METHOD: VOKAN was studied in nine normal subjects using corneo-retinal potential technique and an infrared video camera detection apparatus (ISCAN). VOKAN responses were measured at three angles of pitch head (and body) tilt: 0 degrees (upright), 90 degrees (supine) and 135 degrees (45 degrees below horizontal). The optokinetic stimulus was stripe movement with a velocity of 60 degrees/s. RESULTS: Upward slow phase velocity (SP-Up) VOKAN was evoked in 6/9 subjects (67%) at 0 degrees tilt and at 90 degrees tilt, and in 4/9 (44%) at 135 degrees tilt. Downward slow phase velocity (SP-Down) VOKAN was elicited in 3/9 subjects (33%) at 0 degrees tilt; in 2/9 subjects (22%) at 90 degrees tilt and in 0/9 subjects (0%) at 135 degrees tilt. CONCLUSION: The pitch tilt, as a gravity effect, influences significantly on the appearance and the duration of VOKAN.     

Compressed time and frequency recording of the electrogastrogram by individual wave detection

Electrogastrography (EGG) is a method for recording and analysis of the bioelectrical activity of the stomach, acquired by cutaneous electrodes. The problem of obtaining an EGG signal as free of artefact as possible has recently found some solutions. Good quality recordings of several hours duration can be acquired, often needed, especially if clinical applications are envisaged. Therefore, a next problem to be considered would be time-compressed presentation of the EGG signal without loss of relevant signal characteristics. Relative amplitude changes can be of clinical value, while frequency variations are traditionally regarded as more important. A method for simple compressed presentation of long term EGG recordings, without losing information about the real amplitude and/or frequency changes or transients, is presented. It makes use of detection of successive wave extrema in an EGG. Successive wave amplitudes and durations are measured and momentaneous frequencies are derived. Then a compressed two-trace plot is generated, representing amplitude and frequency variations with respect to time. The method is virtually insensitive to baseline drift, as only the peak amplitudes are detected and followed. A compression factor with respect to the traditional signal recording (1 cm min(-1) or 2 cm min(-1) paper speed) of 5 up to 15 per trace can be obtained.     

Interaction of antithrombin III and thrombin-antithrombin III complex with cultured aortic endothelial cells

The binding of antithrombin III, thrombin, thrombin-antithrombin III complex to endothelial cells was investigated. While the rate of the binding of thrombin to these cells was very rapid, that of antithrombin III was relatively slow and the thrombin-antithrombin III complex was intermediate. Binding kinetics indicated that antithrombin III, like thrombin, showed high affinity to endothelial cells; with a Kd of 3 X 10(-8) M and with 5 X 10(4) binding sites per cell. The dissociation of the inhibitor molecule was also rapid, i.e., approximately 70% bound antithrombin III was released in 2 minutes. Heparin, in a 100-fold molar excess to antithrombin III, or the modification of lysine residues of the inhibitor involved in the interaction with heparin, did not influence the association of antithrombin III with endothelial cells. In addition, antithrombin III did not compete with thrombin blocked in its active center for binding to endothelial cells. It is suggested that the binding sites of endothelial cells are different for thrombin and antithrombin III, and antithrombin III does not bind to these cells through its heparin binding domain.     

Translation,cross-cultural adaptation and validation of the Bulgarian version of the Dizziness Handicap Inventory

Purpose

The aim of the present study was the translation, cross-cultural adaptation and validation of the Dizziness Handicap Inventory in Bulgarian language (DHI-BG).

Methods

Ninety-seven vestibular patients (19 men and 78 women, mean age 45.08 ± 13.85 years) took part in the investigation. All participants were asked to fill in the DHI-BG. Internal consistency was estimated using Cronbach’s alpha and item-total correlation, reproducibility by calculating Bland–Altman’s limits of agreement and intraclass correlation coefficients (ICCs). Associations were estimated by Spearman’s correlation coefficients.

Results

The Cronbach’s alpha for the total score, functional, physical and emotional subscales of DHI-BG were 0.88, 0.75, 0.72 and 0.81. The floor and ceiling effects of the DHI-BG total scale were evaluated with respect to the limits of agreement which were ±9.4–14.53 points. Intraclass correlation coefficients (ICCs) for all scale and subscales were higher than the recommended value of 0.75 and determined good test–retest reliability. The range of items correlation for DHI-BG was from 0.27 (item 12) to 0.72 (item 3). No significant differences were observed in the Cronbach’s alpha coefficients between the DHI-BG and the original version, the German and Italian versions of the questionnaire. The most significant difference was observed in comparison with the German version of DHI. Construct validity presented a moderate correlation between Romberg coefficients and DHI-BG scores and strong correlation between all scores of DHI and the self-perceived disability. The results suggest that DHI-BG scores show a good discriminative validity between groups with different levels of self-assessed disability.

Conclusion

The Bulgarian version of the DHI is a reliable and valid tool in assessing the impact of dizziness on the quality of life in Bulgarian vestibular patients.     

Gender-specific development of auditory information processing in children: an ERP study

ObjectivesThe aim of the present study was to evaluate the effects of gender on sensory and cognitive information processing in children by analyzing auditory event-related potentials (ERPs). The major questions were: (1) do ERPs differ between girls and boys aged 7–10 years, (2) do gender differences in ERPs depend on the development with age, on task-processing demands, and on the development of neuroelectric networks as reflected by the spontaneous EEG?MethodsThirty-six healthy children (18 girls and 18 boys) were divided in two age groups (7- to 8- and 9- to 10-year-old). Boys and girls were pairwise matched for age. Auditory ERPs were analyzed in a passive listening condition (PLC), a simple reaction task (SRT) and a serial learning reaction task (SLRT), in which memory and sensorimotor processes were varied in a balanced way. Cognitive performance, reaction times (RTs), and the spontaneous electroencephalogram (EEG) were also measured.ResultsCognitive performance improved earlier in girls than boys, whereas response speed was not affected by gender. Independent of processing demands, ERP components within 300 ms after stimulation (N1, P2, N2 and P3) increased with development only in the group of girls. For later components, the developmental speeding of the parietal P3b component to task-relevant stimuli also tended to be more expressed in girls than boys, whereas a late frontal negative wave N400–700 was shorter in the girls than boys from the two age groups. Likewise, independently of age, the spontaneous EEG manifested a larger theta activity in girls than boys.ConclusionsDevelopmental changes of basic auditory processing mechanisms strongly depend on gender in children between 7 and 10 years by being faster in girls. This gender-specific development of early ERP components is not modulated by processing demands, cannot be attributed to a faster cognitive maturation of girls, nor can it be explained with the gender-specific maturation of background neuroelectric networks. Rather, it reflects an accelerated functional activation of auditory processing networks in girls. Interestingly, the cognitive development was also faster in girls, but it occurred earlier than the functional activation of auditory processing networks.SignificanceThis study provides evidence for accelerated neuroelectric (as reflected by spontaneous EEG), neurofunctional (as reflected by auditory ERPs), and neurocognitive (as reflected by learning performance) development in 7- to 10-year-old girls than boys.     

Unusual microscopic forms of experimental mesotheliomas

A lightmicroscopic study is made on 36 pleural and 68 peritoneal experimental mesotheliomas induced in white rats by intrapleural and intraperitoneal introduction of asbestos dust. The experimental tumors were compared with 10 spontaneous human mesotheliomas (8 pleural and 2 peritoneal mesotheliomas). The analysis revealed 4 types of morphologically specific experimental mesotheliomas, which could not be referred to the classifications used. In this group are included: a) large cell alveolar, b) small cell alveolar; c) adenocystic; d) with squamous metaplasia and keratinization. The observed unusual experimental lightmicroscopic forms of mesotheliomas support the opinion for great plastic abilities of mesothelium, and the presence of squamous metaplasia with keratinization may be a reason for considering it as a variant of epithelium.     

Functional 5‐HT1a receptor polymorphism selectively modulates error‐specific subprocesses of performance monitoring

Our study investigates the dependence of response monitoring and error detection on genetic influences modulating the serotonergic system. This was done using the event‐related potentials (ERPs) after error (Ne/ERN) and correct trials (Nc/CRN). To induce a sufficient amount of errors, a standard flanker task was used. The subjects (N = 94) were genotyped for the functional 5‐HT1A C(−1019)G polymorphism. The results show that the 5‐HT1A C(−1019)G polymorphism specifically modulates error detection. Neurophysiological modulations on error detection were paralleled by a similar modulation of response slowing after an error, reflecting the behavioral adaptation. The 5‐HT1A −1019 CC genotype group showed a larger Ne and stronger posterror slowing than the CG and GG genotype groups. More general processes of performance monitoring, as reflected in the Nc/CRN, were not affected. The finding that error‐specific processes, but not general response monitoring processes, are modulated by the 5‐HT1A C(−1019)G polymorphism is underlined by a wavelet analysis. In summary, the results suggest a specific effect of the 5‐HT1A C(−1019)G polymorphism on error monitoring, as reflected in the Ne, and suggest a neurobiological dissociation between processes of error monitoring and general response monitoring at the level of the serotonin 1A receptor system. Hum Brain Mapp, 2010. © 2009 Wiley‐Liss, Inc.