Correlations between magnitude and timings of various indices of wave reflection.

<p>AIx, augmentation index; P_b backward pressure, P_b/P_f, the ratio of forward to backward pressure; T_s, the time of the shoulder of the waveform; WRI, wave reflection index. Data are Pearson’s correlation coefficients.</p

Data_Sheet_1_Mitochondrial Translocator Protein (TSPO) Expression in the Brain After Whole Body Gamma Irradiation.PDF

The brain’s early response to low dose ionizing radiation, as may be encountered during diagnostic procedures and space exploration, is not yet fully characterized. In the brain parenchyma, the mitochondrial translocator protein (TSPO) is constitutively expressed at low levels by endothelial cells, and can therefore be used to assess the integrity of the brain’s vasculature. At the same time, the inducible expression of TSPO in activated microglia, the brain’s intrinsic immune cells, is a regularly observed early indicator of subtle or incipient brain pathology. Here, we explored the use of TSPO as a biomarker of brain tissue injury following whole body irradiation. Post-radiation responses were measured in C57BL/6 wild type (Tspo+/+) and TSPO knockout (Tspo–/–) mice 48 h after single whole body gamma irradiations with low doses 0, 0.01, and 0.1 Gy and a high dose of 2 Gy. Additionally, post-radiation responses of primary microglial cell cultures were measured at 1, 4, 24, and 48 h at an irradiation dose range of 0 Gy-2 Gy. TSPO mRNA and protein expression in the brain showed a decreased trend after 0.01 Gy relative to sham-irradiated controls, but remained unchanged after higher doses. Immunohistochemistry confirmed subtle decreases in TSPO expression after 0.01 Gy in vascular endothelial cells of the hippocampal region and in ependymal cells, with no detectable changes following higher doses. Cytokine concentrations in plasma after whole body irradiation showed differential changes in IL-6 and IL-10 with some variations between Tspo–/– and Tspo+/+ animals. The in vitro measurements of TSPO in primary microglial cell cultures showed a significant reduction 1 h after low dose irradiation (0.01 Gy). In summary, acute low and high doses of gamma irradiation up to 2 Gy reduced TSPO expression in the brain’s vascular compartment without de novo induction of TSPO expression in parenchymal microglia, while TSPO expression in directly irradiated, isolated, and thus highly activated microglia, too, was reduced after low dose irradiation. The potential link between TSPO, its role in mitochondrial energy metabolism and the selective radiation sensitivity, notably of cells with constitutive TSPO expression such as vascular endothelial cells, merits further exploration.</p

Wave intensity analysis and pressure separation of the 3 different types of pressure waveform.

<p>The three types of pressure waveform (A, B, C) and their respective augmentation indices (AIx) are shown. The magnitude of the pressure and wave intensity traces have been scaled equally to allow comparison of morphology. Three principal wave S, c⁻₁ and D, forward pressure (P_f) backward pressure (P_b) and the shoulder point (P_s) are indicated.</p

Characteristics of the individuals studied.

<p>Data for men and women are also shown separately.</p><p>Data are mean (SD); p values were calculated using a Student’s t-test comparing women and men. AIx, augmentation index; BMI, body mass index; cSBP, central systolic pressure; DBP, diastolic blood pressure; HR, heart rate, Pb/Pf, the ratio of forward to backward pressure; SBP, systolic pressure; T₁, the time difference between the foot and the shoulder of the waveform; WRI, wave reflection index.</p

Scatterplots of the relationship between age and various indices.

<p>A) Age vs. AIx B) Age vs, Log wave reflection index (WRI) and C) Age vs. peak backward/peak forward pressure (P_b/P_f). Regression lines are derived from data pooled by gender but data points for men (○) and women (•) are indicated separately.</p

Correlations between magnitude and timings of various indices of wave reflection and height.

<p>AIx, augmentation index; P_b backward pressure; P_b/P_f, the ratio of forward to backward pressure; T_s, the time of the shoulder of the waveform; WRI, wave reflection index. Data are Pearson’s correlation coefficients. Data are Pearson’s correlation coefficients.</p

Scatterplots of the relationship between age and wave or waveform timings.

<p>A) time of the shoulder (Ts), B) time of the peak of the reflected wave, c⁻₁ and C) time of P_b. Regression lines are derived from data pooled by gender but data points for men (○) and women (•) are indicated separately.</p

Examples illustrating definitions of measured parameters and indices.

<p>A) pressure waveform (blue) modified from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0059371#pone.0059371-Laurent1" target="_blank">[31]</a> and indicating measured parameters and showing separated forward (black) and backward (red) components. Total pressure is the sum of forward and backward pressure. B) wave intensity analysis, showing principal waves and timings. Wave reflection index (WRI) is calculated as the ratio of the area under c⁻₁ to the area under S wave. Abbreviations c⁻₁, backwards (reflected) compression wave; D, forward decompression wave in late systole; d⁺₁, mid-systolic forward decompression wave, presumed to be a re-reflection of the backward reflected compression wave, c⁻₁; P_b, peak backward pressure; P_f, peak forward pressure; S, forward compression wave associated with ejection in early systole; T_f, time of the foot of the pressure waveform; T_s, time of the shoulder on the pressure waveform; T₁, the time difference between foot and shoulder (T_s−T_f).</p

Comparison of measures of reflection between type A, B and C waveforms.

<p>Data are mean (95% confidence intervals). P values were calculated by analysis of variance.</p

RV-specific antibody responses.

<p>Mice were primed twice with live RV or γ-RV, 2 weeks apart. Serum samples harvested on Day 14 post-2^nd priming and analysed for RV-specific IgG using ELISA. (A) Serial dilutions of serum samples and absorbance readings at 450/620 nm for total IgG. (B) IgG titres in primed groups calculated relative to cut-off value (dotted line), determined using OD values of serum from control mice. Data presented as mean ± SEM (n = 6), and analysed by unpaired t-test (n.s., not significant) (C) Absorbance at 450/620nm for total IgG, IgG1, and IgG2c in serum at 1:200 dilution by ELISA. Data presented as mean ± SEM (n = 4), analysed by One-Way ANOVA (****, p < 0.0001).</p