Coronary Embolic Phenomena: High-Impact, Low-Frequency Events

Coronary embolic phenomena (CEP) are difficult to diagnose yet carry potentially devastating clinical consequences. The goal of this chapter is to outline key processes and pathophysiologic mechanisms underlying CEP, primarily in the context of acute coronary syndrome (ACS). Not surprisingly, most reported cases of CEP occur in the left coronary circulation, but some right-sided events have been reported. Overall, causes include thrombotic, septic/infectious, neoplastic, valve-related, and iatrogenic mechanisms such as air embolization. Coronary angiography remains the definitive diagnostic and therapeutic approach, with computed tomography being increasingly utilized. Transthoracic echocardiography (TTE) should be part of a routine work up for patients with suspected CEP. Holter/event monitoring for atrial fibrillation may also be indicated in patients with embolic phenomena. Clinical management includes procedural restoration of coronary blood flow, followed by appropriate anticoagulation or antiplatelet therapy, in conjunction with appropriate treatment of any arrhythmias or other associated cardiac manifestations or conditions. Timely diagnosis, based on a high index of suspicion (especially in high-risk population) may be important in improving morbidity and mortality in affected patients. Since CEPs are often underdiagnosed and may be due to a number of heterogeneous causes, the need arises for increasing provider awareness of these important phenomena, as well as for the implementation of appropriate clinical management guidelines

Vertical structure of near-bed cross-shore flow velocities in the swash zone of a dissipative beach

Cross-shore velocity profiles are measured at 0.001m vertical resolution and at 100Hz over the lower 0.02-0.07m of the water column in the mid swash zone on a dissipative, macrotidal beach. Swash motion is predominantly at infragravity frequencies and forced by significant wave heights exceeding 1.5m and peak wave periods over 15s. Observations of long duration (> 14s) swashes during two rising tides are used to quantify the vertical structure of cross-shore flow velocities and estimate corresponding bed shear stress and friction coefficients. Analysis is performed on an individual swash event to an elevation of 0.07 m and an ensemble event made up of 24 individual swash events to an elevation of 0.02m. Cross-shore velocities exceed 2 m s-1 and are of a similar magnitude during both the uprush and the backwash. Changes in velocity with elevation indicate that the swash zone boundary layer extends to 0.07m during the strongest flows and is well-represented by the logarithmic model applied to this elevation, except near flow reversal. Maximum bed shear stresses estimated using the logarithmic model are 22 N m-2 and 10 N m-2 for the individual event and ensemble event respectively and mean values are larger during the backwash than the uprush. Mean friction coefficients estimated from equating the logarithmic model and the quadratic drag law are 0.018 and 0.019 for the individual event and ensemble event respectively. Bed shear stress may be underestimated if the logarithmic model is fit to a velocity profile that is only part boundary layer, emphasising the need for high resolution velocity profiles close to the bed for accurate bed shear stress predictions in the swash zone

Rapid Profiling of Marine Notches Using a Handheld Laser Distance Meter

A rapid, single-user profiling method for rocky shores is described. The Leica Disto D8 handheld laser distance meter measures distance up to 100 m and inclination in 360 degrees. It automatically calculates horizontal distance and vertical elevation. Memory storage accommodates data for 30 measurement points, allowing easy plotting of shore profiles. This technique allows even inaccessible, dangerous, and overhanging cliff faces to be evaluated faithfully and within minutes. It is a major improvement over standard methods that often involve risky coasteering and climbing. Examples are given from marine notches in Thailand

Associations among Race/Ethnicity, ApoC-III Genotypes, and Lipids in HIV-1-Infected Individuals on Antiretroviral Therapy

BACKGROUND: Protease inhibitors (PIs) are associated with hypertriglyceridemia and atherogenic dyslipidemia. Identifying HIV-1-infected individuals who are at increased risk of PI-related dyslipidemia will facilitate therapeutic choices that maintain viral suppression while reducing risk of atherosclerotic diseases. Apolipoprotein C-III (apoC-III) gene variants, which vary by race/ethnicity, have been associated with a lipid profile that resembles PI-induced dyslipidemia. However, the association of race/ethnicity, or candidate gene effects across race/ethnicity, with plasma lipid levels in HIV-1-infected individuals, has not been reported. METHODS AND FINDINGS: A cross-sectional analysis of race/ethnicity, apoC-III/apoA-I genotypes, and PI exposure on plasma lipids was performed in AIDS Clinical Trial Group studies (n = 626). Race/ethnicity was a highly significant predictor of plasma lipids in fully adjusted models. Furthermore, in stratified analyses, the effect of PI exposure appeared to differ across race/ethnicity. Black/non-Hispanic, compared with White/non-Hispanics and Hispanics, had lower plasma triglyceride (TG) levels overall, but the greatest increase in TG levels when exposed to PIs. In Hispanics, current PI antiretroviral therapy (ART) exposure was associated with a significantly smaller increase in TGs among patients with variant alleles at apoC-III-482, −455, and Intron 1, or at a composite apoC-III genotype, compared with patients with the wild-type genotypes. CONCLUSIONS: In the first pharmacogenetic study of its kind in HIV-1 disease, we found race/ethnic-specific differences in plasma lipid levels on ART, as well as differences in the influence of the apoC-III gene on the development of PI-related hypertriglyceridemia. Given the multi-ethnic distribution of HIV-1 infection, our findings underscore the need for future studies of metabolic and cardiovascular complications of ART that specifically account for racial/ethnic heterogeneity, particularly when assessing candidate gene effects

Fatigue Life of a NiCr-Coated Powder Metallurgy Disk Superalloy After Varied Processing and Exposures

A protective ductile NiCr coating has shown promise to mitigate oxidation and corrosion attack on superalloy disk alloys. The effects of this coating on fatigue life and failure modes of the disk superalloy are an important concern. The objective of this study was to investigate the fatigue life and failure modes of disk superalloy specimens protected by this coating, using varied pre-coating and post-coating processes. Cylindrical gage fatigue specimens of a powder metallurgy-processed disk superalloy were grit blast or wet blast before being coated with a ductile NiCrY coating, then shot peened at low or medium levels after coating. All were then heat treated, some exposed, and finally all were subjected to fatigue at high temperature. The effects of varied pre-coating treatment, post-coating shot peening, and oxidation plus hot corrosion exposures on fatigue life with the coating were compared

Surface topography of hydroxyapatite affects ROS17/2.8 cells response

Hydroxyapatite (HA) has been used in orthopedic, dental, and maxillofacial surgery as a bone substitute. The aim of this investigation was to study the effect of surface topography produced by the presence of microporosity on cell response, evaluating: cell attachment, cell morphology, cell proliferation, total protein content, and alkaline phosphatase (ALP) activity. HA discs with different percentages of microporosity (< 5%, 15%, and 30%) were confected by means of the combination of uniaxial powder pressing and different sintering conditions. ROS17/2.8 cells were cultured on HA discs. For the evaluation of attachment, cells were cultured for two hours. Cell morphology was evaluated after seven days. After seven and fourteen days, cell proliferation, total protein content, and ALP activity were measured. Data were compared by means of ANOVA and Duncan’s multiple range test, when appropriate. Cell attachment (p = 0.11) and total protein content (p = 0.31) were not affected by surface topography. Proliferation after 7 and 14 days (p = 0.0007 and p = 0.003, respectively), and ALP activity (p = 0.0007) were both significantly decreased by the most irregular surface (HA30). These results suggest that initial cell events were not affected by surface topography, while surfaces with more regular topography, as those present in HA with 15% or less of microporosity, favored intermediary and final events such as cell proliferation and ALP activity

Residual Stresses in a NiCrY-Coated Powder Metallurgy Disk Superalloy

Protective ductile coatings will be necessary to mitigate oxidation and corrosion attack on superalloy disks exposed to increasing operating temperatures in some turbine engine environments. However, such coatings must be resistant to harmful surface cracking during service. The objective of this study was to investigate how residual stresses evolve in such coatings. Cylindrical gage fatigue specimens of powder metallurgy-processed disk superalloy LSHR were coated with a NiCrY coating, shot peened, and then subjected to fatigue in air at room and high temperatures. The effects of shot peening and fatigue cycling on average residual stresses and other aspects of the coating were assessed. Shot peening did induce beneficial compressive residual stresses in the coating and substrate. However, these stresses became more tensile in the coating with subsequent heating and contributed to cracking of the coating in long intervals of cycling at 760 C. Substantial compressive residual stresses remained in the substrate adjacent to the coating, sufficient to suppress fatigue cracking. The coating continued to protect the substrate from hot corrosion pitting, even after fatigue cracks initiated in the coating