Aortic Size at the Time of Type A and Type B Dissections.

BACKGROUND: Aortic diameter at time of dissection remains an indispensable risk-determining characteristic for prophylactic repair of thoracic aortic aneurysms. Histograms of aortic size at the time of dissection have the potential to shed more light on this relationship. METHODS: Size of the thoracic aorta at the time of dissection was determined from imaging of 407 naturally occurring, acute, flap-type ascending or descending aortic dissections treated at 1 institution (1990-2022). Histograms were constructed to depict aortic size at the time of dissection. Data were analyzed by logistic regression. RESULTS: There were 170 (69.11%) of 246 type A dissections (median, 5.07 cm; interquartile range, 4.60-5.67 cm) and 130 (80.75%) of 161 type B dissections (median, 4.2 cm; interquartile range, 3.60-4.87 cm) that occurred at diameters <5.5 cm. By unadjusted regression, factors associated with significantly increased odds of type A dissection at diameters <5.5 cm were female sex (odds ratio [OR], 2.06; P = .023), hypertension (OR, 1.82; P = .036), and smoking (OR, 1.92; P = .029). Patients with bicuspid aortic valve had significantly decreased odds of type A dissection at diameters <5.5 cm (OR, 0.3; P = .047). The recent "left shift" to 5.0 cm in the criterion for ascending aortic intervention could prevent an additional 29.3% of type A dissections. CONCLUSIONS: Aortic diameter at the time of type A dissection is consistent with the new guidelines that recommend surgical intervention at 5.0 cm. Type B dissection occurs at small sizes and cannot be prevented with a size criterion.

KIF6 Trp719Arg Genetic Variant Increases Risk for Thoracic Aortic Dissection.

BACKGROUND: KIF6 (kinesin family member 6), a protein coded by the KIF6 gene, serves an important intracellular function to transport organelles along microtubules. In a pilot study, we found that a common KIF6 Trp719Arg variant increased the propensity of thoracic aortic aneurysms (TAA) to suffer dissection (AD). The present study aims for a definite investigation of the predictive ability of KIF6 719Arg vis à vis AD. Confirmatory findings would enhance natural history prediction in TAA. METHODS: 1108 subjects (899 aneurysm and 209 dissection patients) had KIF6 719Arg variant status determined. RESULTS: The 719Arg variant in the KIF6 gene correlated strongly with occurrence of AD. Specifically, KIF6 719Arg positivity (homozygous or heterozygous) was substantially more common in dissectors (69.8%) than non-dissectors (58.5%) (p = 0.003). Odds ratios (OR) for suffering aortic dissection ranged from 1.77 to 1.94 for Arg carriers in various dissection categories. These high OR associations were noted for both ascending and descending aneurysms and for homozygous and heterozygous Arg variant patients. The rate of aortic dissection over time was significantly higher for carriers of the Arg allele (p = 0.004). Additionally, Arg allele carriers were more likely to reach the combined endpoint of dissection or death (p = 0.03). CONCLUSIONS: We demonstrate the marked adverse impact of the 719Arg variant of the KIF6 gene on the likelihood that a TAA patient will suffer aortic dissection. Clinical assessment of the variant status of this molecularly important gene may provide a valuable "non-size" criterion to enhance surgical decision making above and beyond the currently used metric of aortic size (diameter).

Role of the solvent in the activation of Li2S as cathode material: a DFT study.

Lithium-sulfur batteries are considered one of the possible next-generation energy-storage solutions, but to be commercially available many drawbacks have yet to be solved. One solution with great potentiality is the use of lithium sulfide as cathode material since it can be coupled to Li-free anodes, such as graphite, Si or Sn. Nevertheless, Li2S, like sulfur, is electronically and ionically insulating, with a high activation potential for its initial oxidation step. To overcome this issue, different strategies have been explored, one of them being the use of catalytic surfaces. In the present article, we study using first principles calculations the effect of the dielectric constant of the solvent on the activation energy of the cleavage reaction of Li2S on different catalytic surfaces. To the best of our knowledge, this is the first time that such a study is undertaken. We find that the effect of the solvent should be twofold: on one side, it should decrease the interaction between the Li2S molecule and the surface. On the other side, since the species arising in the dissociation reaction are charged, the solvent should decrease the activation barrier for the dissociation of the Li2S molecule, when compared with the reaction in vacuum. These theoretical findings are discussed in connection with experimental results from the literature, where the behaviour of the Li-S cathode is studied in different solvents.