Computed tomography attenuation of periaortic adipose tissue in abdominal aortic aneurysms

Purpose: To assess periaortic adipose tissue attenuation on CT angiography indifferent abdominal aortic aneurysm disease states.Materials and Methods: In a retrospective observational study from January 2018 to December 2022, periaortic adipose tissue attenuation was assessed on CT angiography in patients with asymptomatic or symptomatic (including rupture) abdominal aortic aneurysms, and control individuals without aneurysms. Adipose tissue attenuation was measured using semi-automated software in periaortic aneurysmal and non-aneurysmal segments of the abdominal aorta, and in subcutaneous and visceral adipose tissue. Periaortic adipose tissue attenuation values between the three groups was assessed using Students t-test and Wilcoxon rank sum test followed by a multi-regression model.Results: Eighty-eight individuals (median age, 70 [IQR, 65-78] years; 78 male and 10 female) were included: 70 patients with abdominal aortic aneurysms (40 asymptomatic and 30 symptomatic including 24 with rupture), and 18 controls. There was no evidence of differences in the periaortic adipose tissue attenuation in the aneurysmal segment in asymptomatic patients versus controls ((-81.44±7 versus -83.27±9 HU, Hounsfield units, P=0.43) and attenuation in non-aneurysmal segments between asymptomatic patients versus controls (-75.43±8 versus -78.81±6 HU, P=0.08). However, symptomatic patients demonstrated higher periaortic adipose tissue attenuation in both aneurysmal (-57.85±7 HU, P<0.0001) and non-aneurysmal segments (-58.16±8 HU, P<0.0001) when compared with the other two groups.Conclusions: Periaortic adipose tissue CT attenuation was not increased in stableabdominal aortic aneurysm disease. There was a generalised increase in attenuation in patients with symptomatic disease, likely reflecting the systemic consequences of acute rupture

International variation in invasive care of the elderly with acute coronary syndromes

Aims To explore variations in invasive care of the elderly with acute coronary syndromes across international practice. Methods and results Using combined populations from the SYMPHONY and 2nd SYMPHONY trials, we describe 30-day cardiac catheterization in elderly (≥75 years; n=1794) vs. younger patients (<75 years; n=14 043) after multivariable adjustment and by region of enrolment. The use of cardiac catheterization and revascularization were not protocol-specified. Elderly patients (median age 78 years) were more often female and more frequently had hypertension, diabetes, prior myocardial infarction, and prior coronary bypass surgery. Overall, they underwent less cardiac catheterization than younger patients [53 vs. 63%; adjusted OR 0.53 (0.46, 0.60)]. The absolute rate of cardiac catheterization in the elderly varied from 77% (vs. 91% in younger patients) in the US cohort to 27% (vs. 41% in younger patients) in the non-US cohort. Revascularization of elderly who underwent cardiac catheterization was also higher in US than non-US cohorts (71.3 vs. 53.6%). There was a significant interaction between the patient age and the use of catheterization across US and non-US regions of enrolment, as well as differences in the predictors of catheterization in the elderly. Despite these findings, after adjustment, 90-day rates of death and death or myocardial infarction (MI) were not significantly different in elderly who underwent catheterization compared with those who did not. Conclusion Although older age is universally predictive of lower use of cardiac catheterization, marked variation in catheterization of the elderly exists across international practice. Demonstrated differences in patterns of use suggest a lack of consensus regarding optimal use of an invasive strategy in the elderl

Structural photoactivation of a full-length bacterial phytochrome

Phytochromes are light sensor proteins found in plants, bacteria, and fungi. They function by converting a photon absorption event into a conformational signal that propagates from the chromophore through the entire protein. However, the structure of the photoactivated state and the conformational changes that lead to it are not known. We report time-resolved x-ray scattering of the full-length phytochrome from Deinococcus radiodurans on micro- and millisecond time scales. We identify a twist of the histidine kinase output domains with respect to the chromophore-binding domains as the dominant change between the photoactivated and resting states. The time-resolved data further show that the structural changes up to the microsecond time scales are small and localized in the chromophore-binding domains. The global structural change occurs within a few milliseconds, coinciding with the formation of the spectroscopic meta-Rc state. Our findings establish key elements of the signaling mechanism of full-length bacterial phytochromes

Methotrexate and relative risk of dementia amongst patients with rheumatoid arthritis:A multi-national multi-database case-control study

Background: Inflammatory processes have been shown to play a role in dementia. To understand this role, we selected two anti-inflammatory drugs (methotrexate and sulfasalazine) to study their association with dementia risk. Methods: A retrospective matched case-control study of patients over 50 with rheumatoid arthritis (486 dementia cases and 641 controls) who were identified from ele

Cellular Imaging of Human Atherosclerotic Lesions by Intravascular Electric Impedance Spectroscopy

Background: Newer techniques are required to identify atherosclerotic lesions that are prone to rupture. Electric impedance spectroscopy (EIS) is able to provide information about the cellular composition of biological tissue. The present study was performed to determine the influence of inflammatory processes in type Va (lipid core, thick fibrous cap) and Vc (abundant fibrous connective tissue while lipid is minimal or even absent) human atherosclerotic lesions on the electrical impedance of these lesions measured by EIS. Methods and Results: EIS was performed on 1 aortic and 3 femoral human arteries at 25 spots with visually heavy plaque burden. Severely calcified lesions were excluded from analysis. A highly flexible micro-electrode mounted onto a balloon catheter was placed on marked regions to measure impedance values at 100 kHz. After paraffin embedding, visible marked cross sections (n = 21) were processed. Assessment of lesion types was performed by Movats staining. Immunostaining for CD31 (marker of neovascularisation), CD36 (scavenger cells) and MMP-3 (matrix metalloproteinase-3) was performed. The amount of positive cells was assessed semi-quantitatively. 15 type Va lesions and 6 type Vc lesions were identified. Lesions containing abundant CD36-, CD31- and MMP-3-positive staining revealed significantly higher impedance values compared to lesions with marginal or without positive staining (CD36+455650 V vs. CD36- 346653 V, p = 0.001; CD31+436643 V vs. CD31- 340655 V, p = 0.001; MMP-3+ 400668 V vs. MMP-3- 323633 V, p = 0.03)