Comparison of ozone uptake and sensitivity between a phytotron study with young beech and a field experiment with adult beech (Fagus sylvatica).

Chamber experiments on juvenile trees have resulted in severe injury and accelerated loss of leaves along with reduced biomass production under chronically enhanced O3 levels. In contrast, the few studies conducted on adult forest trees in the field have reported low O3 sensitivity. In the present study, young beech in phytotrons was more sensitive to O3 than adult beech in the field, although employed O3 regimes were similar. The hypotheses tested were that: (1) differences in O3 uptake were caused by the ontogenetically higher stomatal conductance of young compared to adult trees, (2) the experimental settings in the phytotrons enhanced O3 uptake compared to field conditions, and (3) a low detoxification capacity contributes to the higher O3 sensitivity of the young trees. The higher O3 sensitivity of juvenile beech in the phytotrons is demonstrated to relate to both the experimental conditions and the physiological responsiveness inherent to tree age.

Petrous apex lesions.

OBJECTIVE: The accurate diagnosis of different petrous apex lesions is increasingly common as a result of modern imaging techniques, combining computed tomography and magnetic resonance imaging. The clinical features, diagnostic evaluation, imaging, and treatment outcomes of patients with petrous apex lesions are reviewed. STUDY DESIGN: Retrospective case review. SETTING: Private practice tertiary otologic referral center. PATIENTS: Sixty-six patients treated at the House Ear Clinic in the last 2 decades for a lesion of the petrous apex. Lesions included cholesterol granuloma, cholesteatoma, and chondrosarcoma, among others. Mean follow-up time was 27 months and ranged from 1 month to 10 years. INTERVENTION(S): Cholesterol granulomas were treated with drainage procedures, solid tumors were surgically removed using primarily the middle fossa or infratemporal fossa approaches. RESULTS: The most common presenting symptoms were hearing loss, dizziness, headaches, and tinnitus. Decreased cranial nerve V function was present in 22%. The most common cystic lesion was cholesterol granuloma, which constituted 60% of all lesions in the study, followed by cholesteatoma (9%). Chondrosarcomas were the most common solid lesion (6% of all lesions). Asymmetric pneumatization and retained secretions give radiographic findings commonly overdiagnosed as lesions of the petrous apex. CONCLUSIONS: Lesions of the petrous apex can be diagnosed accurately by CT and MRI and can be divided into cystic and solid lesions. Cholesterol granulomas are by far the most common lesion found in this site and can be drained with minimal morbidity via the infracochlear approach. Solid tumors may require extensive exposure and a combined skull base approach for complete removal.

Primary paraganglioma of the facial nerve canal.

We report two cases of primary paraganglioma of the facial nerve canal. This entity should be considered in patients presenting with facial paresis or pulsatile tinnitus. Paraganglioma should be considered when a lesion appears to arise from the facial nerve canal.