Fasting (8-h) blood samples (7.5 mL SST and 5 mL EDTA tubes, 12.5 mL total per session) will
be collected approximately 180 days and 45 days before flight, on approximate flight day 90,
and 30 days before landing, Return to Earth +0-2 days and 30 days after landing.
Blood samples will be analyzed for vitamin status and one-carbon biochemistry, as previously
described. One blood sample (collected before flight) will be analyzed for approximately 511
SNPs matching the profile of testing from our ongoing research related to optic disc edema.
Serum samples will be analyzed for biochemistry measures evaluating endothelial function,
vitamin status, and oxidative damage.
Nutritional status assessment data, including inflight dietary intake and body mass data,
completed for routine medical requirements will be requested for data sharing. Inflight
medical exercise log data as well as available standard measures data will also be requested
for data sharing. Medication use/Med Logs will also be requested for data sharing.
Vascular function VENDYS-II (Endothelix, Inc) will be used to assess reactive hyperaemia
through changes in fingertip temperature. The test consists of an automated blood pressure
measurement followed by cuff occlusion of the right arm for 2 to 5 min. During this time, the
fingertip temperature in the right hand decreases because of the lack of circulation in the
fingertip. After the cuff is released, blood flow resumes, causing a temperature rebound in
the fingertip in a manner that is proportional to vascular reactivity.
Advanced Glycation End (AGE) Products Skin autofluorescence (SAF) will be analyzed
non-invasively using an AGE reader (Diagnoptics Technologies, Groningen, the Netherlands).
The AGE reader illuminates a skin surface of approximately 4 cm2, guarded against surrounding
light, with an excitation light source with wavelength between 300 and 429 nm. This method is
based on the fluorescent properties of certain AGEs accumulated in dermal tissue.
OCT and OCT-A Optical coherence tomography (OCT) and OCT-angiography (OCT-A) scans will be
acquired using the Spectralis OCT2 (Heidelberg Engineering) before, during, and after flight.
The scan pattern includes 24 B-scans centered in a radial pattern over the optic nerve head,
as well as a 3.5 mm circle scan surrounding the optic nerve head for assessment of retinal
nerve fiber layer thickness and choroid thickness. For OCT-A, five consecutive volume scans
will be obtained in these regions, each containing 216 A-scans. These images will be
registered, and the consecutive B-scans will be used to calculate the decorrelation among the
images to provide split-spectrum amplitude decorrelation angiography (SSADA) images. This
decorrelation between consecutive B-scan images will be used to highlight locations where
there is blood flow. The density of the perfused peripapillary vessels within the various
layers of the retina will be calculated to create a flow density map.