IgE-mediated allergy to fungal allergens in Finland with special reference to Alternaria alternata and Cladosporium herbarum.

BACKGROUND: Alternaria alternata and Cladosporium herbarum are common fungi in outdoor environments, but their clinical significance has not been elucidated in Finland. OBJECTIVE: To evaluate the prevalence of IgE-mediated allergy and clinical outcomes caused by sensitization to fungal allergens in patients with suspected allergy. METHODS: Skin prick tests (SPTs) were performed with C. herbarum in 6,376 patients and also with A. alternata in 1,504 of these patients. SPTs were repeated in 40 patients who showed a positive reaction to either allergen using commercial and in-house extracts. The association of SPT with allergen-specific IgE antibodies in serum was evaluated. Seven patients also underwent a conjunctival challenge test with these fungal allergens. RESULTS: The prevalence of positive SPT results to A. alternata and C. herbarum was low (2.8% and 2.7%, respectively). Among the 40 patients, atopic eczema/dermatitis syndrome was found in 58%, asthma in 44%, and rhinitis in 31%. Most of the patients displayed SPT reactions also to several other fungal allergens, and 75% to 80% showed a positive SPT reaction to allergens of pet animals or pollens. Four patients had a positive reaction to A. alternata and 6 to C. herbarum in the conjunctival challenge test. CONCLUSION: In the Finnish population with allergic symptoms, IgE-mediated sensitization to 2 common fungal allergens was rare and of minor clinical importance. SPT reactions to fungi are mostly observed in patients with multiple sensitivity to various allergens.     

Long-range temporal correlations in electroencephalographic oscillations: Relation to topography, frequency band, age and gender

Presence of long-range temporal correlations in neuronal oscillations is thought to be beneficial for a reliable transfer of information in neuronal networks. In the present study long-range temporal correlations in electroencephalographic (EEG) neuronal oscillations were characterized with respect to their topography, frequency-band specificity (alpha and beta oscillations), gender and age. EEG was recorded in 91 normal subjects (age 20-65 years) in a resting condition. The amplitude of ongoing alpha and beta oscillations was extracted with band-pass filtering and Hilbert transform, and long-range temporal correlations were analyzed with detrended fluctuation analysis. The topography of long-range temporal correlations was comparable for alpha and beta oscillations, showing largest scaling exponents in the occipital and parietal areas. This topography was partially similar to that of the power distribution and a weak positive correlation was observed between long-range temporal correlations and power of neuronal oscillations. Long-range temporal correlations were stronger in alpha than beta oscillations, but only in a few electrode locations in the left hemisphere. In both frequency bands long-range temporal correlations were stronger in males than in females and were largely unaffected by the age of the subjects. It is hypothesized that the idling state of the occipital areas in the closed-eyes condition may explain both large power values and pronounced long-range temporal correlations in this region.     

Alcohol reduces prefrontal cortical excitability in humans: a combined TMS and EEG study.

The effects of alcohol (0.8 g/kg) on the prefrontal cortex were studied in nine healthy subjects using the technique of transcranial magnetic stimulation (TMS) combined with electroencephalography (EEG). A total of 120 magnetic pulses were delivered with a figure-of-eight coil to the left prefrontal cortex at the rate of 0.4-0.7 Hz. The EEG was recorded simultaneously with 60 scalp electrodes (41 electrodes were used for analysis); the TMS-evoked activation was estimated by the area under the global mean field amplitude (GMFA) time curve. TMS caused changes in EEG activity lasting up to 270 ms poststimulus. Alcohol decreased GMFA at 30-270 ms poststimulus (713+/-303 vs 478+/-142 microV ms; p=0.007). Alcohol-induced differences were most pronounced at anterior electrodes. These results suggest that alcohol reduces the excitability in the prefrontal cortex.     

Mapping of multiple muscles with transcranial magnetic stimulation: absolute and relative test–retest reliability

The spatial accuracy of transcranial magnetic stimulation (TMS) may be as small as a few millimeters. Despite such great potential, navigated TMS (nTMS) mapping is still underused for the assessment of motor plasticity, particularly in clinical settings. Here, we investigate the within‐limb somatotopy gradient as well as absolute and relative reliability of three hand muscle cortical representations (MCRs) using a comprehensive grid‐based sulcus‐informed nTMS motor mapping. We enrolled 22 young healthy male volunteers. Two nTMS mapping sessions were separated by 5–10 days. Motor evoked potentials were obtained from abductor pollicis brevis (APB), abductor digiti minimi, and extensor digitorum communis. In addition to individual MRI‐based analysis, we studied normalized MNI MCRs. For the reliability assessment, we calculated intraclass correlation and the smallest detectable change. Our results revealed a somatotopy gradient reflected by APB MCR having the most lateral location. Reliability analysis showed that the commonly used metrics of MCRs, such as areas, volumes, centers of gravity (COGs), and hotspots had a high relative and low absolute reliability for all three muscles. For within‐limb TMS somatotopy, the most common metrics such as the shifts between MCR COGs and hotspots had poor relative reliability. However, overlaps between different muscle MCRs were highly reliable. We, thus, provide novel evidence that inter‐muscle MCR interaction can be reliably traced using MCR overlaps while shifts between the COGs and hotspots of different MCRs are not suitable for this purpose. Our results have implications for the interpretation of nTMS motor mapping results in healthy subjects and patients with neurological conditions.