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The purpose of this study was to investigate the effects of varying ratios of n-6 to n-3 fatty acids in the diets of White Leghorn chickens on tibia bone characteristics [bone mineral density, bone mineral content (BMC), ash bone mineral content, bone morphology, and cortical thickness] and tibia bone strength parameters (ultimate force, bending stress, maximum strain, Young's modulus of elasticity, area under the curve, and moment of inertia). Seventy-five 16-wk-old female White Leghorn chickens were randomly assigned to 1 of 5 dietary ratios of n-6 to n-3 fatty acids: 47.8:1, 18.0:1, 7.6:1, 5.9:1, or 4.7:1. Corn oil was the n-6 fatty acid source, whereas flax oil provided the n-3 fatty acids. Bone density was measured on the left tibia via dual-energy x-ray absorptiometry (DXA) prior to killing and after excision. Bones were ashed in a muffle furnace at 500 degrees F. Tibia bones were broken by using a 3-point bending rig. Results showed no significant effect of diet on bone characteristics. There were no significant differences among diet groups for parameters of bone strength except cortical thickness (P < or = 0.01). Bone mineral content determined by ashing was significantly different by 9.2% (P < or = 0.0001) from BMC determined in vivo by DXA; however, there were no differences in ex vivo BMC and BMC ash, although they were highly correlated (r = 0.99, P < or = 0.0001). We concluded that there was no effect of n-3 fatty acids on tibia bone in mature White Leghorn chickens. The GE Lunar Prodigy DXA instrument significantly underestimated the in vivo BMC in chickens.

Dear Editor; We congratulate Tao et al. [1] for their study entitled 'Relationship between mean platelet volume and reti-nopathy of prematurity'. The authors investigated the association between mean platelet volume (MPV) and the occurrence of type 1 retinopathy of prematurity (ROP) by sampling the peripheral blood platelet indices 1 week prior to laser surgery. They concluded that elevated MPV is associated with the occurrence of type 1 ROP. We think that this is an important finding explaining the role of platelets in the development of ROP, and we would like to express our reservations about the study. It is known that preterm infants have an increased risk of developing some morbidities such as necrotizing enterocolitis (NEC), bronchopulmonary dysplasia (BPD), and intraventricular hemorrhage, as well as than ROP. Dani et al. investigated the relation between MPV and the occurrence BPD, and they reported that high MPV is an independent risk factor for the development of BPD [2]. They also found that the development of ROP is significantly high in the BPD group. Miner et al. investigated the factors affecting the severity of NEC and reported that higher MPV values are associated with the development of higher grade NEC [3]. However, Tao et al. included in the study premature infants that developed ROP and healthy premature infants , but they did not apply any exclusion criteria for the subjects. It is known that morbidities of premature infants such as NEC and BPD last long or develop around the ges-tational age of 33-34 weeks, and we think that these conditions can affect the MPV values. We wonder whether the authors excluded the infants that have such morbidities, and if they did, after the exclusion, whether the difference in MPV is still significant. Conflict of interest None of the authors have any conflict of interest with the submission. References 1. Tao Y, Dong Y, Lu CW, Yang W, Li Q (2015) Relationship between mean platelet volume and retinopathy of prematurity. Graefes Arch Clin Exp Ophthalmol.

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The 2 most common methods to determine resting metabolic rate (RMR) with indirect calorimetry are steady state (SS) and time intervals. Studies have suggested SS more accurately reflects RMR, but further research is needed. Our objective was to compare the bias, precision, and accuracy of SS to time intervals and non-SS measurements in a healthy adult population. Seventy-seven participants were measured for 45 minutes using a Quark RMR. Inclusion criteria included healthy participants aged 18-65 years. Pregnant and lactating women were excluded. Paired t tests compared differences between measures. Bland-Altman plots were used to determine precision. Bias occurred if there was a significant difference between the means. Accuracy was determined by counting the number of absolute differences between SS compared with non-SS and time intervals that were <75 calories. Of 77 participants, 84% achieved SS, and 95% achieved SS by minute 30. Most differences between SS and time intervals were statistically but not practically significant. Bland-Altman plots showed SS measurements were generally lower than any time interval, suggesting SS is more indicative of RMR. Non-SS was significantly more biased ( P = .0005), less precise (spread of limits of agreement was 269 calories), and less accurate (65%) than SS. We conclude that non-SS is not equivalent to SS. We also conclude that using 5-minute SS is more indicative of RMR than any time interval that was tested in healthy populations. If SS cannot be achieved, we recommend repeating the measurement.