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Structural state of erythrocyte membranes from patients with AD was studied.
Erythrolysis, Malondialdehyde (MDA) content, and lipid bilayer microviscosity was
used as a membrane structural characteristic. Erythrolysis and MDA content exhibit
Lipid Per Oxidation (LPO) level. Membranes microviscosity was measured by elec-
tron paramagnetic resonance spin labeling of 2,2,6,6-tetramethyl-4-capryloyl-oxypi-
peridine-1-oxyl (lipidic label) 5,6-Benzo-2,2,6,6-tetramethyl-1,2,3,4-tetrahydro-g-
carbolyn-3-oxide (proteinic label). It was established in erythrocyte membrane both
components (lipidic and proteinic) À uidity was increased of all patients with AD. Three
groups were sorted out in terms of LPO. The LPO intensity was enhanced in the ¿ rst
group. This group was characterized by high hemolysis and MDA content before and
after incubation. The MDA content and hemolysis were increased during incubation
period. The LPO intensity was decreased in two other groups. Low erythrolysis and
no changes during incubation period were observed in the second group. Ratio MDA/
peroxide hemolysis was notably greater than unity. Third group was characterized by
increased mechanical hemolysis by decreasing the erythrolysis and MDA content dur-
ing incubation period.
We had already shown that erythrocyte membrane structural alterations can exhibit
the changes in the brain membranes [6, 7]. Therefore, it was interesting to study struc-
tural state of the erythrocyte membranes from human with AD.
8.2 EXPERIMENTAL
Erythrocyte membrane structural state of the ten patients with different AD severity
was studied. As they control the red blood cells of fifty one peoples over 40 years
old was used. Erythrocytes were isolated from blood by means of differential cen-
trifugation at 1,000 g for 10 min. Membrane fluidity in two regions of lipid bilay-
er was estimated with the help of Erythrocyte sedimentation rate (ESR) technique.
2,2,6,6-tetramethyl-4-capryloyl-oxypiperidin-1-oxyl (probe I) and 5,6-benzo-2,2,6,6-
tetramethyl-1,2,3,4-tetrahydro-Ȗ-carboline-3-oxyl (probe II) were used as a probes.
Probes spin correlation time (
τ
ɫ
) were calculated from obtained spectra [8, 9], which
correspond to the period of radical's reorientation about ʌ/2. A probe spin correlation
time is proportional to the membrane microviscosity or inversely proportional to fluid-
ity. It is known that probe II localizes mostly in near protein areas, probe I in protein
free areas of lipid bilayer surface (2-4 ǖ) [10], thus the probe spin correlation time can
show lipid-protein interaction in membranes. In addition, erythrocyte lysis and MDA
content (measuring units was mmole per million of erythrocytes) are changes were
determined as a LPO rate index. The MDA content and hemolysis before (mechanical
hemolysis (MH)) and after (peroxile hemolysis (PH)) incubation at 37°C for 10 min
were measured by the reaction with tiobarbituric acid.
8.3 DISCUSSION AND RESULTS
Obtained results shown that erythrocytes membrane both the regions (lipid and pro-
tein) fluidity were increased twice above normal (Figure 1). This fact testifies as a
failure in the system of LPO homeostasis in these membranes [11, 12]. Burlakova E.
B. has proposed the memory model with the membranes structure as the primary fac-
tor [13]. Based on this model memory impairments during AD can be explained. As
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