It is unknown whether gender influences the atherosclerotic plaque characteristics (APCs) of lesions of varying angiographic stenosis severity. This study evaluated the imaging data of 303... Show moreIt is unknown whether gender influences the atherosclerotic plaque characteristics (APCs) of lesions of varying angiographic stenosis severity. This study evaluated the imaging data of 303 symptomatic patients from the derivation arm of the CREDENCE (Computed TomogRaphic Evaluation of Atherosclerotic Determinants of Myocardial IsChEmia) trial, all of whom underwent coronary computed tomographic angiography and clinically indicated nonemergent invasive coronary angiography upon study enrollment. Index tests were interpreted by 2 blinded core laboratories, one of which performed quantitative coronary computed tomographic angiography using an artificial intelligence application to characterize and quantify APCs, including percent atheroma volume (PAV), low-density noncalcified plaque (LD-NCP), noncalcified plaque (NCP), calcified plaque (CP), lesion length, positive arterial remodeling, and high-risk plaque (a combination of LD-NCP and positive remodeling ≥1.10); the other classified lesions as obstructive (≥50% diameter stenosis) or nonobstructive (<50% diameter stenosis) based on quantitative invasive coronary angiography. The relation between APCs and angiographic stenosis was further examined by gender. The mean age of the study cohort was 64.4 ± 10.2 years (29.0% female). In patients with obstructive disease, men had more LD-NCP PAV (0.5 ± 0.4 vs 0.3 ± 0.8, p = 0.03) and women had more CP PAV (11.7 ± 1.6 vs 8.0 ± 0.8, p = 0.04). Obstructive lesions had more NCP PAV compared with their nonobstructive lesions in both genders, however, obstructive lesions in women also demonstrated greater LD-NCP PAV (0.4 ± 0.5 vs 1.0 ± 1.8, p = 0.03), and CP PAV (17.4 ± 16.5 vs 25.9 ± 18.7, p = 0.03) than nonobstructive lesions. Comparing the composition of obstructive lesions by gender, women had more CP PAV (26.3 ± 3.4 vs 15.8 ± 1.5, p = 0.005) whereas men had more NCP PAV (33.0 ± 1.6 vs 26.7 ± 2.5, p = 0.04). Men had more LD-NCP PAV in nonobstructive lesions compared with women (1.2 ± 0.2 vs 0.6 ± 0.2, p = 0.02). In conclusion, there are gender-specific differences in plaque composition based on stenosis severity. Show less
OBJECTIVEThis study evaluates the relationship between atherosclerotic plaque characteristics (APCs) and angiographic stenosis severity in patients with and without diabetes. Whether APCs differ... Show moreOBJECTIVEThis study evaluates the relationship between atherosclerotic plaque characteristics (APCs) and angiographic stenosis severity in patients with and without diabetes. Whether APCs differ based on lesion severity and diabetes status is unknown.RESEARCH DESIGN AND METHODSWe retrospectively evaluated 303 subjects from the Computed TomogRaphic Evaluation of Atherosclerotic Determinants of Myocardial IsChEmia (CREDENCE) trial referred for invasive coronary angiography with coronary computed tomographic angiography (CCTA) and classified lesions as obstructive (≥50% stenosed) or nonobstructive using blinded core laboratory analysis of quantitative coronary angiography. CCTA quantified APCs, including plaque volume (PV), calcified plaque (CP), noncalcified plaque (NCP), low-density NCP (LD-NCP), lesion length, positive remodeling (PR), high-risk plaque (HRP), and percentage of atheroma volume (PAV; PV normalized for vessel volume). The relationship between APCs, stenosis severity, and diabetes status was assessed.RESULTSAmong the 303 patients, 95 (31.4%) had diabetes. There were 117 lesions in the cohort with diabetes, 58.1% of which were obstructive. Patients with diabetes had greater plaque burden (P = 0.004). Patients with diabetes and nonobstructive disease had greater PV (P = 0.02), PAV (P = 0.02), NCP (P = 0.03), PAV NCP (P = 0.02), diseased vessels (P = 0.03), and maximum stenosis (P = 0.02) than patients without diabetes with nonobstructive disease. APCs were similar between patients with diabetes with nonobstructive disease and patients without diabetes with obstructive disease. Diabetes status did not affect HRP or PR. Patients with diabetes had similar APCs in obstructive and nonobstructive lesions.CONCLUSIONSPatients with diabetes and nonobstructive stenosis had an association to similar APCs as patients without diabetes who had obstructive stenosis. Among patients with nonobstructive disease, patients with diabetes had more total PV and NCP. Show less
Thiel, J. van; Khan, M.A.; Wouters, R.M.; Harris, R.J.; Casewell, N.R.; Fry, B.G.; ... ; Richardson, M.K. 2022
Convergence is the phenomenon whereby similar phenotypes evolve independently in different lineages. One example is resistance to toxins in animals. Toxins have evolved many times throughout the... Show moreConvergence is the phenomenon whereby similar phenotypes evolve independently in different lineages. One example is resistance to toxins in animals. Toxins have evolved many times throughout the tree of life. They disrupt molecular and physiological pathways in target species, thereby incapacitating prey or deterring a predator. In response, molecular resistance has evolved in many species exposed to toxins to counteract their harmful effects. Here, we review current knowledge on the convergence of toxin resistance using examples from a wide range of toxin families. We explore the evolutionary processes and molecular adaptations driving toxin resistance. However, resistance adaptations may carry a fitness cost if they disrupt the normal physiology of the resistant animal. Therefore, there is a trade-off between maintaining a functional molecular target and reducing toxin susceptibility. There are relatively few solutions that satisfy this trade-off. As a result, we see a small set of molecular adaptations appearing repeatedly in diverse animal lineages, a phenomenon that is consistent with models of deterministic evolution. Convergence may also explain what has been called 'autoresistance'. This is often thought to have evolved for self-protection, but we argue instead that it may be a consequence of poisonous animals feeding on toxic prey. Toxin resistance provides a unique and compelling model system for studying the interplay between trophic interactions, selection pressures and the molecular mechanisms underlying evolutionary novelties. Show less
We have examined sequences from the ligand-binding domain of the nicotinic acetyl choline receptor (nAChR) in 148 vertebrate species. We are in interested in this receptor because the α-neurotoxins... Show moreWe have examined sequences from the ligand-binding domain of the nicotinic acetyl choline receptor (nAChR) in 148 vertebrate species. We are in interested in this receptor because the α-neurotoxins of many venomous snakes binds to this receptor in its location at the neuromuscular junction in all vertebrates. Furthermore, some animals have evolved resistance to snake venoms and show modifications in the ligand binding domain of the nAChR which inhibit the binding of snake α-neurotoxins. Our analysis has shown that numerous vertebrate species, most of which were not previously known to possess α-neurotoxin resistance, do actually contain resistance-related modifications. These modifications are present in most of the taxa in our dataset, with the unexpected exclusion of the birds. It was particularly surprising to us that the snake-specialist predatory birds Circaetus pectoralis (black-chested snake eagle) and Sagittarius serpentarius (secretary bird) did not possess resistance modifications. There were also relatively few resistance-related mutations within the mammals. By contrast, there were multiple convergent evolutions of the well-characterised N-glycosylation motif within the squamate reptiles—particularly the snakes. We also identified a number of sites under positive selection, such as mutations to the proline subsite. Future functional testing will be needed to validate that these modifications do indeed confer resistance. To provide functional confirmation that resistance-related modifications do indeed reduce susceptibility to toxins, we used developmental bioassays. These assays showed that two species possessing resistance-related modifications of the nAChR (stickleback and bearded dragon) were less susceptible to the toxic effects of cobra venom than two species that lacked such modifications (zebrafish and chicken). In summary, we demonstrate that the range of mechanisms along with the phylogenetic distribution of resistance to snake α-neurotoxin appears to be more extensive than was previously appreciated. It also shows strong evidence of the convergent evolution of the same resistance mutations in independent linages. Our findings also support the notion that the mutations we have identified in this thesis may represent adaptive change in response to selective pressures exerted by α-neurotoxic snake venoms in an evolutionary arms race. Thus, we conclude that the evolutionary arms race between predator and prey appears to be a pervasive feature of the trophic interactions surrounding venomous snakes, which is shaping the molecular evolution of the nAChR in the vertebrates. Show less
Key PointsQuestionAre atherosclerotic plaque measurements associated with physiologic measures of invasive fractional flow reserve? FindingsIn this analysis of the CREDENCE clinical trial that... Show moreKey PointsQuestionAre atherosclerotic plaque measurements associated with physiologic measures of invasive fractional flow reserve? FindingsIn this analysis of the CREDENCE clinical trial that included 612 patients, nonobstructive and obstructive measures of atherosclerotic plaque were significantly associated with invasive fractional flow reserve. A comprehensive set of atherosclerotic plaque features improved the accuracy of classifying vessel-specific reduced fractional flow reserve vs rest/stress myocardial perfusion imaging measurements. MeaningUsing coronary computed tomographic angiography for detection of atherosclerotic plaque features associated with coronary physiology may improve diagnostic certainty and guide clinical management of symptomatic patients.ImportanceStress imaging has been the standard for diagnosing functionally significant coronary artery disease. It is unknown whether novel, atherosclerotic plaque measures improve accuracy beyond coronary stenosis for diagnosing invasive fractional flow reserve (FFR) measurement. ObjectiveTo compare the diagnostic accuracy of comprehensive anatomic (obstructive and nonobstructive atherosclerotic plaque) vs functional imaging measures for estimating vessel-specific FFR. Design, Setting, and ParticipantsControlled clinical trial of diagnostic accuracy with a multicenter derivation-validation cohort of patients referred for nonemergent invasive coronary angiography. A total of 612 patients (64 [10] years; 30% women) with signs and symptoms suggestive of myocardial ischemia from 23 sites were included. Patients were recruited from 2014 to 2017. Data analysis began in August 2018. InterventionsPatients underwent invasive coronary angiography with measurement of invasive FFR, coronary computed tomographic angiography (CCTA) quantification of atherosclerotic plaque and FFR by CT (FFR-CT), and semiquantitative scoring of rest/stress myocardial perfusion imaging (by magnetic resonance, positron emission tomography, or single photon emission CT). Multivariable generalized linear mixed models were derived and validated calculating the area under the receiver operating characteristics curve. Main Outcomes and MeasuresThe primary end point was invasive FFR of 0.80 or less. ResultsOf the 612 patients, the mean (SD) age was 64 (10) years, and 426 (69.9%) were men. An invasive FFR of 0.80 or less was measured in 26.5% of 1727 vessels. In the derivation cohort, CCTA vessel-specific factors associated with FFR 0.80 or less were stenosis severity, percentage of noncalcified atheroma volume, lumen volume, the number of lesions with high-risk plaque (>= 2 of low attenuation plaque, positive remodeling, napkin ring sign, or spotty calcification), and the number of lesions with stenosis greater than 30%. Fractional flow reserve-CT was not additive to this model including stenosis and atherosclerotic plaque. Significant myocardial perfusion imaging predictors were the summed rest and difference scores. In the validation cohort, the areas under the receiver operating characteristic curve were 0.81 for CCTA vs 0.67 for myocardial perfusion imaging (P<.001). Conclusions and RelevanceA comprehensive anatomic interpretation with CCTA, including quantification of obstructive and nonobstructive atherosclerotic plaque, was superior to functional imaging in the diagnosis of invasive FFR. Comprehensive CCTA measures improve prediction of vessel-specific coronary physiology more so than stress-induced alterations in myocardial perfusion. Trial RegistrationClinicalTrials.gov Identifier: NCT02173275.This analysis of the CREDENCE trial compares the diagnostic accuracy of comprehensive anatomic (obstructive and nonobstructive atherosclerotic plaque) vs functional imaging measures for estimating vessel-specific fractional flow reserve. Show less
Venomous snakes are important subjects of study in evolution, ecology, and biomedicine. Many venomous snakes have alpha-neurotoxins (alpha-neurotoxins) in their venom. These toxins bind the alpha-1... Show moreVenomous snakes are important subjects of study in evolution, ecology, and biomedicine. Many venomous snakes have alpha-neurotoxins (alpha-neurotoxins) in their venom. These toxins bind the alpha-1 nicotinic acetylcholine receptor (nAChR) at the neuromuscular junction, causing paralysis and asphyxia. Several venomous snakes and their predators have evolved resistance to alpha-neurotoxins. The resistance is conferred by steric hindrance from N-glycosylated asparagines at amino acids 187 or 189, by an arginine at position 187 that has been hypothesized to either electrostatically repulse positively charged neurotoxins or sterically interfere with alpha-neurotoxin binding, or proline replacements at positions 194 or 197 of the nAChR ligand-binding domain to inhibit alpha-neurotoxin binding through structural changes in the receptor. Here, we analyzed this domain in 148 vertebrate species, and assessed its amino acid sequences for resistance-associated mutations. Of these sequences, 89 were sequenced de novo. We find widespread convergent evolution of the N-glycosylation form of resistance in several taxa including venomous snakes and their lizard prey, but not in the snake-eating birds studied. We also document new lineages with the arginine form of inhibition. Using an in vivo assay in four species, we provide further evidence that N-glycosylation mutations reduce the toxicity of cobra venom. The nAChR is of crucial importance for normal neuromuscular function and is highly conserved throughout the vertebrates as a result. Our research shows that the evolution of alpha-neurotoxins in snakes may well have prompted arms races and mutations to this ancient receptor across a wide range of sympatric vertebrates. These findings underscore the inter-connectedness of the biosphere and the ripple effects that one adaption can have across global ecosystems. Show less
