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INTRODUCTION: Urinary calcium (Uca) levels in space reflect bone loss and kidney stone risk and could be measured using portable devices. This project evaluated the repeatability of Uca measurements to assess how many repeated measurements would be needed to detect significant urinary calcium elevations in space.METHODS: A total of six subjects collected 24-h urine samples weekly for 8 wk and took 500 mg of oral calcium carbonate and 400 IU of vitamin D daily in week 7 and 8. Uca concentration was analyzed using a calcein-based system. The effect of the intake of calcium and vitamin D on Uca levels and the correlation between first void concentration and 24-h mass were assessed with linear mixed effect models. The reproducibility coefficient (RPC) for Uca was determined using Bland-Altman analysis on pairs of measurements at different time points.RESULTS: Oral supplementation did not significantly affect 24-h mass. First void concentration correlated with 24-h mass. The 24-h mass RPCs were 167.0, 116.8, and 108.1 mg for 1-, 2-, and 3-wk average measurements. First void concentration RPCs were 90.6, 76.6, and 72.8 mg L1. Skylab astronauts 24-h mass increased by 88.9 76.0, 123.5 58.3, 142.2 56.5, and 159.9 83.4 mg after 1, 2, 3, and 4 wk in flight.DISCUSSION: Averaging multiple Uca measurements reduced variability effectively and allowed increases likely to be seen in space to be detected. Consecutive Uca measurements could be tracked over time in space to assess the effectiveness of the countermeasure program. First void concentration could potentially be used rather than 24-h collections.Ren J, Stankovic AS, Knaus DA, Phillips SD, Kynor DB, Buckey JC. Urinary calcium for tracking bone loss and kidney stone risk in space. Aerosp Med Hum Perform. 2020; 91(9):689696.

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BackgroundA unique syndrome affecting young adults of unexplained hearing loss often associated with uncorrectable poor visual acuity and lower extremity numbness is endemic in Dar es Salaam. This study characterised the hearing loss, associated it with other symptoms, and gathered information on potential causes. MethodsForty-seven patients (23 men, 24 women) <40 years old with a symptom consistent with the syndrome, negative syphilis test, and no head injury history were recruited from Muhimbili National Hospital. 18 controls (10 men, 8 women) were recruited from the same neighborhoods as patients. Hearing ability and cochlear outer hair cell function (distortion-product otoacoustic emissions (DPOAEs)) were assessed, as were visual acuity and colour vision. Peripheral neuropathy was evaluated using the Michigan Neuropathy Screening Instrument (MNSI), and physical examination. Blood C-reactive protein levels and toenail trace metal concentrations were measured. Environmental exposures were elicited using a questionnaire. Patients with at least two of the following signs were defined as having the syndrome: poor hearing with normal DPOAEs, vision not correctable to better than 20/30, or a MNSI score greater than 4. Results29 participants met the case definition. C-reactive protein (CRP) levels did not differ between groups but manganese, cobalt and tin levels were each greater in the cases than controls. No other environmental exposure differences were noted. ConclusionsToenail manganese, cobalt, and tin levels were higher in those with the syndrome. These metals are potential neurotoxins suggesting a possible environmental origin for this unique and debilitating syndrome.

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