Astrochemical relevance of VUV ionization of large PAH cations. ASTRONOMY AND ASTROPHYSICS 2020;641:A98. [PMID: 33154599 PMCID: PMC7116310 DOI: 10.1051/0004-6361/202038139]

CONTEXT

As a part of interstellar dust, polycyclic aromatic hydrocarbons (PAHs) are processed by the interaction with vacuum ultra-violet (VUV) photons that are emitted by hot young stars. This interaction leads to the emission of the well-known aromatic infrared bands but also of electrons, which can significantly contribute to the heating of the interstellar gas.

AIMS

Our aim is to investigate the impact of molecular size on the photoionization properties of cationic PAHs.

METHODS

Trapped PAH cations of sizes between 30 and 48 carbon atoms were submitted to VUV photons in the range of 9 to 20 eV from the DESIRS beamline at the synchrotron SOLEIL. All resulting photoproducts including dications and fragment cations were mass-analyzed and recorded as a function of photon energy.

RESULTS

Photoionization is found to be predominant over dissociation at all energies, which differs from an earlier study on smaller PAHs. The photoionization branching ratio reaches 0.98 at 20 eV for the largest studied PAH. The photoionization threshold is observed to be between 9.1 and 10.2 eV, in agreement with the evolution of the ionization potential with size. Ionization cross sections were indirectly obtained and photoionization yields extracted from their ratio with theoretical photoabsorption cross sections, which were calculated using time-dependent density functional theory. An analytical function was derived to calculate this yield for a given molecular size.

CONCLUSIONS

Large PAH cations could be efficiently ionized in H i regions and provide a contribution to the heating of the gas by photoelectric effect. Also, at the border of or in H ii regions, PAHs could be exposed to photons of energy higher than 13.6 eV. Our work provides recipes to be used in astronomical models to quantify these points.

P6336Plasma proteomic profile predicts survival in heart failure with reduced ejection fraction

Background

Whether the plasma proteome can predict the course of heart failure (HF) and has incremental value to established predictors is uncertain.

Methods

Patients meeting Framingham HF criteria with history of reduced ejection fraction (n=1017) were prospectively enrolled in a registry and donated fasting blood samples. Plasma underwent analysis on the SOMAscan proteomic discovery platform, quantifying 4789 proteins using standard assay and quality controls. Patients were randomly divided into derivation (n=681) and validation (n=336) cohorts. We derived a proteomic risk score (PRS) in the derivation cohort using Lasso-penalized Cox regression and then tested it in the validation cohort. Both models were adjusted for an establish HF clinical risk score (MAGGIC) and NTproBNP. We assessed risk stratification improvement in the validation cohort by comparing models with and without PRS using the model C statistic, continuous net reclassification index (NRI), integrated discrimination index (IDI), and the median improvement in risk score (MIRS).

Results

Overall 47.5% of patients were African American, 35.2% were female, mean ejection fraction was 34.8%, and average age was 67.9 years. After median follow-up of 3.6 years, there were 296 deaths (194 in derivation and 102 in validation). Optimized modeling defined a 32 protein PRS (hazard ratio [HR] 2.33, p<2.00E-16) which was also statistically significant when tested in the validation cohort (PRS HR=1.19, p=4.87E-02) and showed some improvement in risk stratification (Table).

Methods Variables Estimate 95% CI P Validation Testing MAGGIC 1.06 1.027, 1.092 2.84E-04 NTproBNP 1.84 1.430, 2.359 1.88E-06 PRS 1.19 1.001, 1.408 4.87E-02 Risk Stratification Assessment C-statistic improvement 0.012 −0.076, 0.101 8.30E-01 IDI 0.034 0.007, 0.095 <2.00E-16 Continuous-NRI 0.286 −0.062, 0.475 9.00E-02 Median Improvement in Risk Score 0.015 0.001, 0.078 2.00E-02

Conclusion

A plasma multi-protein predictive score can improve risk stratification in HF patients on top of a validated clinical score and NTproBNP. Additional investigation is warranted to define mechanisms underlying individual proteins and explore proteomic clinical applications.

What's ahead in glucose monitoring? New techniques hold promise for improved ease and accuracy

Advances in blood glucose monitoring have made it easier, more comfortable, and more practical for patients to monitor frequently. The new meters for intermittent monitoring are smaller and less dependent on technical aptitude than older models. They require less blood, and many provide downloadable information for glucose analysis. Data systems used with new meters provide valuable information that can dramatically improve glycemic control. Continuous glucose sensing (figure 4) is another major breakthrough in management of diabetes. Current systems allow only retrospective analyses, but real-time readings should be available in the near future. Such technological advances hold promise for preventing both hypoglycemia and hyperglycemia and for reducing the risk of long-term complications associated with diabetes. An artificial, mechanical islet cell may be the big next step toward bringing this disease under control. By combining continuous glucose monitoring data with continuous insulin delivery via an external or an implantable insulin pump, the outlook promises to be much brighter for patients with type 1 diabetes.

Safety and feasibility of a cardiac support device

The Cardiac Support Device (CSD), a preformed-knitted polyester device surgically placed over the cardiac ventricles, prevents left ventricular (LV) remodeling and improves LV ejection fraction (EF) in dogs with heart failure (HF). This study was designed to examine the safety of the CSD in patients with advanced HF. As of December 31, 1999, the CSD was implanted into 22 patients with myocardial disease. Ten patients had concomitant mitral valve repair, two patients had valve replacement (one patient aortic and one patient mitral), one patient had LV assist device (LVAD) placement, and eight patients received only the CSD. The CSD was placed while on bypass with the heart beating, attached to the epicardium groove, and tailored anteriorly to snugly fit the ventricles. There were no intraoperative deaths or complications. Two patients died early from non-CSD-related causes 4 and 23 days postoperatively; one late death occurred. Of the remaining 19 patients, none had any CSD-related adverse events during an average 3.5 +/- 0.4 month follow-up. All patients had completed 3-month follow-up. No patients had evidence of constrictive and/or restrictive physiology. Mitral valve regurgitation (MVR) improved in all patients. [table: see text] Initial findings indicate that the CSD is safe and improves heart failure symptoms and LV function. Additional studies and longer follow-up are needed to confirm these results.

Electrocardiographic presentation of blacks with first myocardial infarction does not explain race differences in thrombolysis administration

BACKGROUND

Previous studies have suggested that thrombolysis is used less often in blacks than in whites. However, whether the greater prevalence of contraindications or less specific electrocardiographic manifestations of myocardial infarction (MI) account for this difference is unclear.

METHODS AND RESULTS

We studied 498 consecutive patients (32% blacks) with first MI. Initial electrocardiograms were analyzed, blinded to race and outcome, for ST-segment deviation and bundle branch block to determine eligibility for thrombolysis. The relation of electrocardiographic eligibility for thrombolysis and actual use of thrombolysis in both races was explored. Among blacks, 45% received thrombolysis compared with 66% of whites (P <.001). A similar proportion of blacks and whites were eligible for thrombolysis (59% and 66% respectively, P =. 116), but 62% of electrocardiography-eligible blacks were treated with thrombolysis compared with 75% of whites (P =.016). After accounting for eligibility for electrocardiography and other clinical variables likely to affect the decision to administer thrombolysis by means of conditional logistic regression, blacks were still less likely to receive thrombolysis (relative risk 0.73; 95% confidence interval 0.55 to 0.97).

CONCLUSIONS

We conclude that the differences in thrombolysis administration to blacks and whites are not accounted for by differences in electrocardiographic presentation or other measured variables. Unmeasured differences in clinical presentation of MI may explain racial differences in thrombolysis and merits further study.

Ventricular remodeling. Mechanisms and prevention

The changes that take place in the structure and form of the left ventricle have become closely related to increase in clinical events in patients with heart failure. These changes are included in the term remodeling and occur as a response to the initial loss of left ventricular muscle mass. The mechanisms that initiate and maintain this remodeling process have become of great importance since a variety of effective pharmacologic agents have become available. A more complete understanding of remodeling has the potential of preventing the progression of heart failure. This article considers the various aspects of left ventricular remodeling including the cardiomyocytes, the myocardial interstitium, the importance that apoptosis plays the remodeling process.

Force-velocity-length relations in man expressed by a single hemodynamic expression: the ejection rate of change of power at peak tension

An attempt was made to develop a hemodynamic indicator of pump function that relates to the contractile characteristics of cardiac muscle. The ejection rate of change of power has ideal characteristics for this purpose. It is firmly based upon theories of fluid dynamics and its derivation is free of assumptions related to heart structure and function. It is measured as p dQ/dt + Q dp/dt, where p = pressure and Q = flow. When measured at peak tension, the ejection rate of change of power was (12.3 +/- 0.8) X 10(8) dynes cm sec-2 in 11 patients with abnormal ventricular performance (P less than 0.001). Studies in dogs showed no effect of preload or afterload. This suggests a relation to characteristics of muscle fibers, which was shown. If one assumes a thin wall sphere, the ejection rate of change of power at peak tension reduces to the following function of tension (T), fiber length (2 pi r), and rate of shortening (2 pi dr/dt): d(power)/dt = 8 pi T](dr/dt)2 + r d2r/dt2[. Thus, the contractile characteristics of muscle fibers (force, velocity and tension) are related in an uncomplicated fashion by a single and highly discriminating hemodynamic indicator of ventricular performance, the ejection rate of change of ventricular power measured at peak tension.