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.
