The ingestion of different dietary proteins by humans induces large changes in the plasma tryptophan ratio, a predictor of brain tryptophan uptake and serotonin synthesis.

BACKGROUND & AIMS: The ingestion by rats of different proteins causes large differences in the plasma ratio of tryptophan to other large neutral amino acids, which predicts brain tryptophan uptake and serotonin synthesis. We evaluated in humans whether ingesting these proteins also produces large excursions in the tryptophan ratio. METHODS: Fasting males (n = 6) ingested V-8 Juice containing 40 g of α-lactalbumin, gluten, zein or starch. Blood was drawn before and at 30 min intervals after ingestion for 4 h; tryptophan and other large neutral amino acids were quantitated. RESULTS: Pre-meal plasma tryptophan was ~50 nmol/ml; the tryptophan ratio was ~0.010. α-Lactalbumin increased plasma tryptophan (3-fold) and the tryptophan ratio (50%); starch did not change either tryptophan variable, while gluten caused a modest (25%) and zein a large reduction (50%) in plasma tryptophan. Gluten and zein reduced the tryptophan ratio. The maximal difference in the tryptophan ratio occurred between α-lactalbumin and zein and was large (~3-fold). CONCLUSION: Since the plasma tryptophan ratio predicts brain tryptophan uptake and serotonin synthesis in rats, the differences in the ratio produced in humans by these proteins may modify serotonin synthesis, and perhaps elicit serotonin-linked changes in behavior.

Change in proptosis following extraocular muscle surgery: effects of muscle recession in thyroid-associated orbitopathy.

PURPOSE: To evaluate the effect of strabismus surgery on proptosis in patients with thyroid-associated orbitopathy. METHODS: The medical records of 22 consecutive patients with thyroid-associated orbitopathy undergoing strabismus surgery were reviewed. Data pertaining to the number of muscles operated on, amount of muscle recession, prior orbital decompression, and exophthalmometry were evaluated. RESULTS: Thirty-eight eyes in 22 patients with thyroid-associated orbitopathy were studied before and after strabismus surgery. The mean change in exophthalmometry following strabismus surgery in all eyes was +0.6 mm (p < 0.01). Eyes with prior decompression averaged a 0.9 mm increase following strabismus surgery (p < 0.01); those without decompression averaged a 0.2 mm decrease (p = 0.658). In eyes that underwent two rectus muscle recessions the increase in Hertel measurements averaged 1.2 mm; when only one muscle was recessed, the average increase was 0.2 mm. In the eyes with muscle recession < or =5 mm, the mean exophthalmometric increase was 0.7 mm. When a muscle recession of more than 5 mm was performed, the exophthalmometry showed a mean increase of 0.5 mm. CONCLUSIONS: Strabismus surgery on patients with thyroid-associated orbitopathy can worsen proptosis, especially in those with prior decompression. When planning for orbital decompression, the surgeon should consider this effect. Moreover, patients should be made aware of the possible changes to their appearance.