America's growing elderly population has led to an increase in research on the aging process, including the relationship of muscle retention to health. Monitoring muscle development at the molecular level is an excellent complement to traditional whole‐muscle assessment methods. 3‐Methylhistidine (3‐MH) is an amino acid derivative and breakdown product of muscle protein. Urinary 3‐MH levels vary with diet and exercise, meriting its use as a molecular marker of muscle turnover. A method to perform rapid quantitation of 3‐MH in urine was developed using single‐ion monitoring (SIM) LC‐MS. After being spiked with an added internal standard and desalted by solid‐phase extraction, samples were analyzed by SIM LC‐MS, quantified versus the added internal standard and normalized versus a ubiquitous internal standard, creatinine. The use of LC‐MS eliminates the need for derivatization as required in established HPLC fluorescence and GC‐MS techniques. Constructed calibration curves plotting the ratio of 3‐MH to internal standard show a strong linear relationship with 3‐MH concentrations, with R‐squared values as high as 0.9983. The method presented is not only effective for monitoring 3‐MH, but holds potential for simultaneous monitoring of additional urine metabolites with run times of approximately 13 minutes.
There are several techniques of monitoring essential tremors, but there is not yet a standard method developed for the field. A quantitative way to track effects of medication and/or lifestyle treatment would be beneficial for future research in prevention or regression of essential tremors. The two methods evaluated are acoustic tremor monitoring (ATM) and rhythmic spirals (RS). The novel ATM measurement quantifies frequency and amplitude quickly and cost effectively. The tremor patient holds a microphone close to a speaker playing a single frequency tone. The Doppler Effect caused by the shaking microphone distorts the sound recording, and the encoded tremor information can be retrieved by using the Fast-Fourier Transform algorithm. The second method, RS, can be used by patients at home to measure frequency. The RS method is similar to the classic Archimedes spirals, but uses a different form and is timed which allows for the calculation of tremor frequency. The RS and ATM methods produce statistically similar frequency measurements, although ATM has greater precision.
KEYWORDS: Essential Tremors, Archimedes Spiral, Accelerometry, Spiral Analysis, Acoustic Tremor Monitoring, Rhythmic Spirals.
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