Chemosensory event-related potentials in relation to side of stimulation, age, sex, and stimulus concentration.

OBJECTIVE: For chemosensory event-related potentials (ERP) significant effects of age and sex have been demonstrated. The aim of the present study was to assess the effects of stimulus concentration, side of stimulation, and sex on the topographical distribution of chemosensory ERP in a large group of subjects stratified for different age groups. In addition, psychophysical measures of both olfactory and trigeminal function should be assessed in greater detail compared to previous work. METHODS: A total of 95 healthy subjects participated in the study. Olfactory functions were tested using the 'Sniffin' Sticks' comprising tests of odor identification, odor discrimination, and odor threshold. Trigeminal sensitivity was assessed on a psychophysical level using a lateralization paradigm. ERP to the olfactory stimulant H2S and the trigeminal irritant CO2 were recorded; stimuli were presented in different concentrations to the left and right nostril. RESULTS: Olfactory thresholds exhibited an age-related increase while the outcome of psychophysical trigeminal tests was not significantly affected by age. In contrast, there was no significant main effect of the factor 'sex' for olfactory tests, while women scored higher than men in the trigeminal task. ERP to olfactory and trigeminal stimuli exhibited a relationship to stimulus concentration, age, and sex with youngest women showing largest amplitudes and shortest latencies. There was no significant main effect of left- or right-sided stimulation on ERP. Measures of olfactory function were found to correlate with parameters of olfactory ERP even when controlling for the subject's age. In addition, correlations between scores in the lateralization task and parameters of the trigeminal ERP were found. CONCLUSIONS: Based on electrophysiological data obtained in a large sample size the present results established an age-related loss of olfactory and trigeminal function, which appears to be almost linear. Further, the present results emphasize that responses to chemosensory stimuli are related to sex, while the side of stimulation does not play a major role in the presently used paradigm. Finally, these data establish the lateralization paradigm as a psychophysical tool to investigate intranasal trigeminal function. SIGNIFICANCE: The present results obtained in a representative group of healthy subjects establishes a comprehensive set of data, which will serve as reference for future work in this area of research.     

Multilevel surgery for obstructive sleep apnea: short-term results.

OBJECTIVE: To determine the efficacy of a new multilevel surgical protocol for obstructive sleep apnea (OSA). STUDY DESIGN AND SETTING: Sixty patients with moderate to severe OSA because of multilevel pharyngeal obstruction were enrolled into this prospective, controlled clinical trial after clinical examination, endoscopy, and polysomnography. Surgery included uvulaflap, tonsillectomy, hyoid suspension, and radiofrequency treatment of the tongue base (group A). A second group did not receive hyoid suspension (group B). In both groups, nasal surgery was performed if necessary. Polysomnography and Epworth Sleepines Scale (ESS) were recorded at baseline and 2 to 15 months after surgery. RESULTS: In group A, the mean apnea-hypopnea index (AHI) decreased significantly after surgery (38.9 +/- 20.0 vs 20.7 +/- 20.6, P < 0.0001), whereas in group B the AHI did not. All secondary variables (minimal oxygen saturation, mean oxygen saturation, arousal index), and the ESS significantly improved in group A with only changes in arousal index and ESS reaching levels of significance in group B. CONCLUSION: The presented protocol including the hyoid suspension proved to be effective in the treatment of OSA, whereas surgery without hyoid suspension was less successful. EBM rating: B-2b.     

Androgen receptor YAC transgenic mice carrying CAG 45 alleles show trinucleotide repeat instability

X-linked spinal and bulbar muscular atrophy (SBMA) is caused by a CAG repeat expansion in the first exon of the androgen receptor (AR) gene. Disease-associated alleles (37-66 CAGs) change in length when transmitted from parents to offspring, with a significantly greater tendency to shift size when inherited paternally. As transgenic mice carrying human AR cDNAs with 45 and 66 CAG repeats do not display repeat instability, we attempted to model trinucleotide repeat instability by generating transgenic mice with yeast artificial chromosomes (YACs) carrying AR CAG repeat expansions in their genomic context. Studies of independent lines of AR YAC transgenic mice with CAG 45 alleles reveal intergenerational instability at an overall rate of approximately 10%. We also find that the 45 CAG repeat tracts are significantly more unstable with maternal transmission and as the transmitting mother ages. Of all the CAG/CTG repeat transgenic mice produced to date the AR YAC CAG 45 mice are unstable with the smallest trinucleotide repeat mutations, suggesting that the length threshold for repeat instability in the mouse may be lowered by including the appropriate flanking human DNA sequences. By sequence-tagged site content analysis and long range mapping we determined that one unstable transgenic line has integrated an approximately 70 kb segment of the AR locus due to fragmentation of the AR YAC. Identification of the cis - acting elements that permit CAG tract instability and the trans -acting factors that modulate repeat instability in the AR YAC CAG 45 mice may provide insights into the molecular basis of trinucleotide repeat instability in humans.