Stable isotopes have proven to be a useful tool for deciphering food webs, examining migration patterns and determining nutrient resource allocation. In order to increase the descriptive power of isotopes, an increasing number of studies are using them to model tissue turnover. However, these studies have, mostly by necessity, been largely limited to laboratory experiments and the demand for an easier method of estimating tissue turnover in the field for a large variety of organisms remains. In this study, we have determined the turnover rate of blood in mice and rats using stable isotope analysis, and compared these rates to the metabolic rates of the animals. Rats (Rattus norvegicus) (n=4) and mice (Mus musculus) (n=4) were switched between isotopically distinct diets, and the rate of change of delta(13)C and delta(15)N in whole blood was determined. Basal metabolic rates (as CO(2) output and O(2) consumption per unit time, normalized for mass) were determined for the rats and mice. Rats, which were an order of magnitude larger and had a slower metabolic rate per unit mass than mice (0.02 vs. 0.14 O(2)/min/g), had a slower blood turnover than mice for (13)C (t (1/2 )=24.8 and 17.3 days, respectively) and (15)N (t (1/2 )=27.7 and 15.4 days, respectively). A positive correlation between metabolic rate and blood isotopic turnover rate was found. These are the only such data for mammals available, but the literature for birds shows that mass and whole-body metabolic rates in birds scale logarithmically with tissue turnover. Interestingly, the mammalian data graph separately from the bird data on a turnover versus metabolic rate plot. Both mice and rat tissue in this study exhibited a slower turnover rate compared to metabolic rate than for birds. These data suggest that metabolic rate may be used to estimate tissue turnover rate when working with organisms in the field, but that a different relationship between tissue turnover and metabolism may exist for different classes of organisms.

Objectives: Non-selective laryngeal reinnervation (NSLR) using the ansa cervicalis to the recurrent laryngeal nerve (RLN) is a promising treatment option for pediatric unilateral neuronal vocal fold movement impairment (VFMI). The aim is to describe our clinical outcomes with this technique and to identify preoperative characteristics that may predict postoperative voice outcomes.Methods: This is a cohort study of pediatric patients with unilateral neuronal VFMI, who underwent NSLR from March 2012 to July 2018. Pre-and postoperative Pediatric Voice Related Quality of Life (PVRQOL) questionnaires, Consensus Auditory Perceptual Evaluation of Voice (CAPE-V) ratings, and objective voice measures were obtained. In addition, patients underwent preoperative laryngeal electromyography (LEMG).Results: Thirty-two patients were identified. Twenty-one had complete data sets for analysis. The mean duration of VFMI was 9.02 years (range 1.1-26.1 years). There were significant improvements in PVRQOL (P = .0005), in all CAPE-V subsets (P ≤ .0001 to .0195), mean and maximum intensities (P = .0342 and 0.0110, respectively), cepstral peak prominence (P = .0001), and cepstral spectral index of dysphonia (P ≤ .0001). A worse preoperative LEMG correlated with a greater change in maximum phonation time (P = .0162) and maximum intensity (P = .0346). Age at injury and duration of injury had no significant impact on voice outcomes; however, patients with concurrent posterior glottic insufficiency did have smaller changes in PVRQOL (P = .012).Conclusion: NSLR is an effective treatment for pediatric unilateral neuronal VFMI even many years after initial RLN injury. LEMG may help predict voice outcomes of reinnervation in pediatric patients, but further data is still needed.

The relaxing incision described here creates a flap that allows for reconstruction of a larger range of skull base defects.

Questions remain pertinent to the otolaryngologist regarding the ideal management of children with Down syndrome. Additional studies are necessary, to optimize understanding and treatment of this complex population, in particular as opportunities develop with technological advances.

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