Summary Aim: We investigated whether additional application of “cold” iodine after therapy with radioiodine could result in a prolongation of the effective half life of iodine-131 and would thus lead to an increase of the effective thyroid radiation dose. Methods: Time-activitycurves after therapy with radioiodine were analysed in 25 patients (16 women, 9 men). Nine patients suffered from autonomously functioning thyroid nodules, 5 from autonomous multinodular goiter and 11 from Graves’ disease. These patients had an effective half life shorter than 4 days resulting in an undertreatment of > 20% with respect to the desired effective thyroid radiation dose. 2-4 days after therapy with radioiodine all patients received “cold” iodine for three days in a dose of 3 × 200 μg per day. Results: In 14 of the 25 patients an increase of the effective half life was observed. Patients with an autonomously functioning thyroid nodule showed a mean increase of the effective thyroid radiation dose of 40 ± 44 Gy, patients with toxic multinodular goiter of 29 ± 30 Gy and patients with Graves’ disease of 37 ± 37 Gy. Conclusion: Additional application of “cold” iodine after therapy with radioiodine can prolong the effective half life in selected patients. We suspect a correlation with the thyroid iodine pool. This will be the basis for further investigations hopefully resulting in a better patient preselection to determine who might respond to this therapy.

The effect of vitamin A deficiency in guinea pigs on noise-induced temporary threshold shift (TTS) was evaluated after short (15 min) acoustic overstimulation with a moderate (90 dB) broad-band white noise. Some guinea pigs were fed ad libitum a purified diet deficient in vitamin A (VAD group) until biochemical signs of deficiency occurred. A second, control group (VA group) received the same diet as well as 100 IU vitamin A daily by pharyngeal tube. Cochlear potentials were recorded by special computerized equipment using implanted electrodes. Before acoustic stimulation, a baseline value was determined with a test stimulus [90 dBA (A-filter according to usual DIN instructions)] corresponding to that for TTS measurements. Noise-induced changes were determined by calculating the changes in latency and amplitude of the N1-signal of the compound action potential (CAP) at various times (1, 3, 5, 7, 11 min) after termination of acoustic stimulation in comparison with baseline values. Statistical analysis of the CAP data showed that the VAD group had significantly smaller amplitudes and increased latency of the N1-potential after acoustic stimulation and that the VA group did not show a significant change in amplitude or latency. The reduction in N1-amplitude and N1-latency in the VAD group reflects changes in inner ear hair cell activity. We conclude that vitamin A deficiency increases the sensitivity of the inner ear to noise and that this increased sensitivity increases the probability of noise-induced hearing loss.

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Zusammenfassung Ziel: Es war das Ziel, mit einem lodstoffwechselmodell Aspekte des lodstoffwechsels theoretisch zu analysieren. Methode: Hierzu wurde ein Dreikompartimentmodell entwickelt. Hiermit wurde der Einfluß physiologischer und pharmakologischer Iodmengen auf den 131 I-Uptake der Schilddrüse untersucht, zusätzlich die Ausscheidung nach Radio-iodtherapie. Ergebnisse: Die Analysen zeigen, daß eine wenigstens dreitägige stationäre Aufnahme zur Radioiodtherapie sinnvoll ist sowie eine iodarme Diät wenige Tage zuvor. Hinsichtlich einer lodblockade der Schilddrüse bei einem Reaktorunfall werden die Auswirkungen der deutschen Empfehlungen mit den WHO-Richtlinien verglichen. Schlußfolgerung: Das lodstoffwechselmodell gestattet eine Analyse auch dort, wo aus ethischen, meßtechnischen und anderen Limitationen Messungen am Menschen nicht oder nur eingeschränkt möglich sind.

To estimate the role of vitamin A on ciliated cells we investigated whether ciliated cells undergo any alteration during vitamin A deficiency. The epithelia examined include the ciliated cells of the respiratory tract and the ciliated sensory cells of the inner ear, the tongue, and the olfactory cells. This part of the paper will describe the ciliated epithelium of the tracheobronchial tract and its relation to vitamin A status. During vitamin A deficiency a partial loss of ciliae can be observed before any squamous metaplasia (which usually occurs during longer lasting vitamin A deficiency) develops. The scanning electron microscopic data illustrate the altered surface of the epithelium during vitamin A deficiency better than transmission electron microscopy.