Subject dosing
We make up doses for studies here in Aberdeen and supply these pre-weighed to collaborators, based on supplied subject characteristics. If you are making up your own doses then it is important to follow strict procedures to ensure the dose is not contaminated and can be delivered quantitatively to the subjects. Normally human subjects are dosed using 10APE oxygen18 which has 99.9% deuterium added to it. It is best if a batch of dose solution is made up for an entire experiment.
The individual doses then need to be aliquotted into dose bottles. At this stage it is important to know exactly how much isotope has been put into each dose bottle. The doses are prepared in line with the body weights of the subjects. If exact subject weights are known then a personalised dose can be prepared for a given subject. If individual weights are not known then we use an average expected weight.
Dosing is oral in human studies and urine samples are typically collected. Once a background urine sample has been collected the dose can be provided. It is important that you ensure that they drink the entire dose. Record the exact weight of dose given to each subject, their body weight and the time of dosing.
Sample Collection
Collecting multiple samples is best for human subjects to generate a detailed elimination curve.
DO NOT collect the first void of the day. The bladder is a reservoir that integrates the signal over the period since the bladder was last emptied. This is why the first urine of the day should be avoided as the integration period for this sample is much longer than all other samples in the day.
Always collect a background urine sample prior to dosing.
After dosing, the timing of the initial sample is important. If dosing occurs early in the day this can be 4-6 hours later. If dosing occurs later in the day then waiting overnight and then collecting the second urine void the following day is acceptable.
We then recommend collecting urine samples daily or every second day over the course of 10-14 days at exactly the same time.
Urine is best collected in a wide necked plastic or glass bottle with a cap that has an internal seal. The volume of the vessel does not need to be large but the bottle neck needs to be wide enough that the subject can urinate directly into it. This means that typically sample bottles can contain 100-200 mls of urine. It is easiest if the sample is then alloquoted into 2ml cryotubes in duplicate and 1 tube is kept by the research team and one tube transferred to the laboratory.
Urine samples should be carefully labelled with the date, time and subject ID and frozen at -20℃.
They should be shipped to our laboratory on dry ice. If this is a problem, then urine samples can be sealed in capillaries.