Hyper-Raman spectroscopy of biomolecules.

The hyper-Raman scattering (HRS) spectra of biologically significant molecules (D-glucose, L-alanine, L-arabinose, L-tartaric acid) in aqueous solutions are reported. The HRS spectra were measured using a picosecond laser at 532 nm operating at a MHz repetition rate. High signal to noise spectra were collected with a commercial spectrometer and CCD without resonant, nanoparticle, or surface enhancement. The HRS peak frequencies, relative intensities, band assignments, and depolarization ratios are examined. By comparing HRS to Raman scattering (RS) and infrared absorption spectra we verify that the IR-active vibrational modes of the target molecules are observed in HRS spectra but come with substantially different peak intensities. The HRS of the biomolecules as well as water, dimethyl sulfoxide, methanol, and ethanol were deposited into a data repository to support the development of theoretical descriptions of HRS for these molecules. Depositing the spectra in a repository also supports future dual detection RS, HRS microscopes which permit simultaneous high-spatial-resolution vibrational spectroscopy of IR-active and Raman-active vibrational modes.

Predictive Value of Body Mass Index in Minimally Invasive Mitral Valve Surgery.

BACKGROUND: With this study we aimed to analyze if the separate consideration of body mass index (BMI) could provide any superior predictive values compared with the established risk scores in isolated minimally invasive mitral valve surgery (MIMVS). This might facilitate future therapeutic decision-making, e.g., regarding the question surgery versus transcatheter mitral valve repair (TMVr). METHODS: We assessed the relevance of BMI in non-underweight patients who underwent isolated MIMVS. The risk predictive potential of BMI for mortality and several postoperative adverse events was assessed in 429 consecutive patients. This predictive potential was compared with that of European System for Cardiac Outcome Risk Evaluation II (EuroSCORE II) and the Society of Thoracic Surgeons score (STS score) using a comparative receiver operating characteristic curve analysis. RESULTS: BMI was a significant numeric predictor of wound healing disorders (p = 0.001) and proved to be significantly superior in case of this postoperative adverse event compared with the EuroSCORE II (p = 0.040) and STS score (p = 0.015). Except for this, the predictive potential of BMI was significantly inferior compared with that of the EuroSCORE II and STS score for several end points, including 30-day (p = 0.029 and p = 0.006) and 1-year (p = 0.012 and p = 0.001) mortality. CONCLUSION: Therefore, we suggest that, in the course of decision-making regarding the right treatment modality for non-underweight patients with isolated mitral valve regurgitation, the sole factor of BMI should not be given a predominant weight.

Coherent anti-Stokes Raman scattering imaging of microcalcifications associated with breast cancer.

Chemical imaging of calcifications was demonstrated in the depth of a tissue. Using long wavelength excitation, broadband coherent anti-Stokes Raman scattering and hierarchical cluster analysis, imaging and chemical analysis were performed 2 mm below the skin level in a model system. Applications to breast cancer diagnostics and imaging are discussed together with the methods to further extend the depth and improve the spatial resolution of chemical imaging.

New insights into a hydrogen bond: hyper-Raman spectroscopy of DMSO-water solution.

Hydrogen bonding plays an essential role in biological processes by stabilizing proteins and lipid structures as well as controlling the speed of enzyme catalyzed reactions. Dimethyl sulfoxide-water (DMSO-H2O) solution serves as a classical model system by which the direct and indirect effects of hydrogen bonding between water hydrogens and the sulfoxide functional group can be explored. The complex transition from self-bonding to heterogeneous bonding is important, and multiple spectroscopic approaches are needed to provide a detailed assessment of those interactions. In this report, for the first time, hyper-Raman scattering was successfully employed to investigate molecular interactions in DMSO-H2O system. We measured the improper blueshift of the C-S and C-H stretching modes of DMSO caused by partial charge transfer and enhanced bond polarization. By detecting differences in the frequency shifts of C-S and C-H modes for low DMSO concentrations (<33 mol%) we find evidence of the intermolecular bonds between water and the DMSO methyl groups. We exploit the high sensitivity of hyper-Raman scattering to the low frequency librations of H2O to observe a change in librational mode population providing insight into existing questions about the coordination of H2O around DMSO molecules and the formation of the H2O shell around DMSO molecules proposed in prior simulation studies. These results demonstrate that hyper-Raman spectroscopy can be a practical spectroscopic technique to study the intermolecular bonding of model systems and test claims about model system bonding generated by theoretical calculations.

Risk and Consequences of Postoperative Delirium in Cardiac Surgery.

BACKGROUND: Delirium is a common complication after cardiac surgery that leads to increased costs and worse outcomes. This retrospective study evaluated the potential risk factors and postoperative impact of delirium on cardiac surgery patients. METHODS: One thousand two hundred six patients who underwent open-heart surgery within a single year were included. Uni- and multivariate analyses of a variety of pre, intra-, and postoperative parameters were performed according to differences between the delirium (D) and nondelirium (ND) groups. RESULTS: The incidence of delirium was 11.6% (n = 140). The onset of delirium occurred at 3.35 ± 4.05 postoperative days with a duration of 5.97 ± 5.36 days. There were two important risk factors for postoperative delirium: higher age (D vs. ND, 73.1 ± 9.04 years vs. 69.0 ± 11.1 years, p < 0.001) and longer aortic cross-clamp time (D vs. ND, 69.8 ± 49.9 minutes vs. 61.6 ± 53.8 minutes, p < 0.05). We found that delirious patients developed significantly more frequent postoperative complications, such as myocardial infarction (MI) (D vs. ND, 1.43% [n = 3] vs. 0.28% [n = 2], p = 0.05), cerebrovascular accident (D vs. ND, 10.7% [n = 15] vs. 3.75% [n = 40], p < 0.001), respiratory complications (D vs. ND, 16.4% [n = 23] vs. 5.72% [n = 61], p < 0.001), and infections (D vs. ND, 36.4% [n = 51] vs. 16.0% [n = 170], p < 0.001). The hospital stay was longer in cases of postoperative delirium (D vs. ND, 23.2 ± 13.6 days vs. 17.4 ± 12.8 days, p < 0.001), and fewer patients were discharged home (D vs. ND, 56.0% [n = 65] vs. 66.8% [n = 571], p < 0.001). CONCLUSIONS: Because the propensity for delirium-related complications is high after cardiac surgery, a practical, preventative strategy should be developed for patients with perioperative risk factors, including higher age and a longer cross-clamp time.

Highly efficient tunable picosecond deep ultraviolet laser system for Raman spectroscopy.

We present a narrowband laser system tunable from 219 to 236 nm for deep ultraviolet (DUV) Raman spectroscopy. The demonstrated laser system produces 6.7 ps nearly transform-limited pulses with energy up to 0.36 µJ at 100 kHz repetition rate. The system consists of a two-stage optical parametric amplifier (OPA) of a narrowband continuous wave diode laser and subsequent frequency conversion to the DUV radiation. We achieve more than 300 mW in the signal wave using ${{\rm LiB}_3}{{\rm O}_5}$LiB3O5 (LBO) and ${{\rm BaB}_2}{{\rm O}_4}$BaB2O4 (BBO) crystals, with the total 2.7 W pump after the two-stage OPA. We reach 12% conversion efficiency of the OPA signal wave into the DUV radiation using type-I phase matching in the BBO crystal. Finally, we demonstrate the applicability of the system for DUV Raman spectroscopy by collecting a high dynamic range, high spectral resolution spontaneous Raman spectrum of air.

Lightweight Raman spectroscope using time-correlated photon-counting detection.

Raman spectroscopy is an important tool in understanding chemical components of various materials. However, the excessive weight and energy consumption of a conventional CCD-based Raman spectrometer forbids its applications under extreme conditions, including unmanned aircraft vehicles (UAVs) and Mars/Moon rovers. In this article, we present a highly sensitive, shot-noise-limited, and ruggedized Raman signal acquisition using a time-correlated photon-counting system. Compared with conventional Raman spectrometers, over 95% weight, 65% energy consumption, and 70% cost could be removed through this design. This technique allows space- and UAV-based Raman spectrometers to robustly perform hyperspectral Raman acquisitions without excessive energy consumption.

Simple approach to high-fidelity tunable narrow-band pulse generation.

Tunable narrow-band short-pulse coherent emission can be generated by the optical parametric amplification of a seeded continuous wave (CW) laser. However, the residual CW pedestal can affect the accuracy of the optical measurements and the exact interpretation of the experimental data. We demonstrate a simple approach to removing the residual CW seed in a frequency tunable, seeded parametric amplification setup in the nanosecond regime by adding an additional parametric amplification stage which is seeded by an idler wave from the first stage. We validate this method by using a pump-probe experiment in an atomic vapor. Our results show the elimination of an atomic vapor hyperfine pumping signal after the CW pedestal has been removed.

Electronically tunable coherent Raman spectroscopy using acousto-optics tunable filter.

Fast and sensitive Raman spectroscopy measurements are imperative for a large number of applications in biomedical imaging, remote sensing and material characterization. In this report, by introducing an electronically-tunable acousto-optical filter as a wavelength selector, we demonstrated a novel instrumentation to the broadband coherent Raman spectroscopy. System's tunability allows assessing Raman transitions ranging from <400 cm(-1) to 4500 cm(-1). We validated the use of the new instrumentation by collecting coherent anti-Stokes spectra and stimulated Raman spectra of various samples.

Flow cytometry using Brillouin imaging and sensing via time-resolved optical (BISTRO) measurements.

A novel concept of Brillouin imaging and sensing via time-resolved optical (BISTRO) measurements is introduced for flow cytometry applications. The system affords robust, maintenance-free and high-speed elasticity-sensitive measurements.

Detecting anthrax in the mail by coherent Raman microspectroscopy.

In this report, we show the collection of spatial information through a turbid medium by coherent Raman microspectroscopic imaging. In particular, the technique is capable of identifying anthrax endospores inside a sealed paper envelope.

Chemical analysis of molecular species through turbid medium.

Subsurface analysis of chemical species is imperative for biomedical diagnostics and imaging, homeland security, and pharmaceutical and other industries; however, the access to the object of interest is often obscured by an optically scattering medium which limits the ability to inspect the chemical composition of the sample. In this report, we employ coherent Raman microspectroscopy in a combination with a hierarchical cluster analysis to mitigate the effect of scattering and demonstrate the identification of multiple chemical species.

Coherent anti-Stokes Raman spectroscopy utilizing phase mismatched cascaded quadratic optical interactions in nonlinear crystals.

We experimentally investigated the nonlinear optical interaction between the instantaneous four-wave mixing and the cascaded quadratic frequency conversion in commonly used nonlinear optical KTP and LiNbO3 with the aim of a possible background suppression of the non-resonant background in coherent anti-Stokes Raman scattering. The possibility of background-free heterodyne coherent anti-Stokes Raman scattering microspectroscopy is investigated at the interface formed by a liquid (isopropyl alcohol) and a nonlinear crystal (LiNbO3).

Nonresonant background suppression in coherent anti-Stokes Raman spectroscopy through cascaded nonlinear optical interactions.

We propose and experimentally validate a technique for four-wave mixing background suppression in coherent anti-Stokes Raman spectroscopy. It is based on the interaction of the signals generated from the Kerr third-order nonlinearity and the cascaded quadratic process in a nonlinear crystal. Theoretical analysis agrees well with the experimental results, which provide a quantitative assessment of different contributions and allow extraction of the nonlinearity parameters.

Continuous-Wave Stimulated Raman Scattering (cwSRS) Microscopy.

Stimulated Raman scattering (SRS) microscopy is a powerful tool for chemically-sensitive non-invasive optical imaging. However, ultrafast laser sources, which are currently employed, are still expensive and require substantial maintenance to provide temporal overlap and spectral tuning. SRS imaging, which utilizes continuous-wave laser sources, has a major advantage, as it eliminates the cell damage due to exposure to the high-intensity light radiation, while substantially reducing the cost and complexity of the set-up. As a proof-of-principle, we demonstrate microscopic imaging of dimethyl sulfoxide using two independent, commonly used lasers, a diode-pumped, intracavity doubled 532-nm laser and a He-Ne laser operating at 632.8-nm.

Sex differences and estrogen effects in cardiac mitochondria in human aortic stenosis and in the mouse heart.

Introduction: Sex differences in the adaptation to pressure overload have been described in humans, as well as animal models, and have been related to sex-specific expression of mitochondrial genes. We therefore tested whether sex differences in cardiac mitochondrial respiration exist in humans with aortic stenosis (AS). We also examined whether these potential differences may be at least partially due to sex hormones by testing if mitochondrial respiration is affected by estrogen (17ß-estradiol (E2)). Methods: Consecutive patients undergoing transapical aortic valve implantation (TAVI) (women, n = 7; men, n = 10) were included. Cardiac biopsies were obtained during TAVI and used directly for mitochondrial function measurements. Male and female C57BL/6J mice (n = 8/group) underwent sham surgery or gonadectomy (GDX) at the age of 2 months. After 14 days, mice were treated once with intraperitoneally injected vehicle (placebo), 17ß-estradiol (E2), estrogen receptor alpha (ERα) agonist [propyl pyrazole triol (PPT)], or ER beta (ERß) agonist (BAY-1214257). Thereafter, mitochondrial measurements were performed directly in cardiac skinned fibers from isolated left ventricles and musculus solei. Results: Mitochondrial State-3 respiration was higher in female than that in male human heart biopsies (15.0 ± 2.30 vs. 10.3 ± 2.05 nmol/mL/min/mg, p< 0.05). In the mouse model, mitochondrial State-3 respiration decreased significantly after GDX in female (27.6 ± 1.55 vs. 21.4 ± 1.71 nmol/mL/min/mg; p< 0.05) and male hearts (30.7 ± 1,48 vs. 23.7 ± 2,23 nmol/mL/min/mg; p< 0.05). In ovariectomized female mice, E2 and ERß-agonist treatment restored the State-3 respiration to intact placebo level, whereas ERα-agonist treatment did not modulate State-3 respiration. The treatment with E2, ERα-, or ERß-agonist did not modulate the State-3 respiration in GDX male mice. Conclusion: We identified sex differences in mitochondrial respiration in the diseased human heart. This is in alignment with known sex differences in the gene expression and proteome level at the functional level. E2 and ERß affect cardiac mitochondrial function in the mouse model, suggesting that they may also contribute to the sex differences in the human heart. Their roles should be further investigated.

Chemically Specific Imaging Through Stimulated Raman Photoexcitation and Ultrasound Detection: Minireview.

A powerful combination of chemically specific Raman excitation and deep tissue ultrasound imaging holds the promise to attain spatially resolved distribution of chemical compounds inside the scattering medium. In this report, an attempt is made to evaluate the recent achievements and possible challenges with an eye on potential clinical applications.

Impact of the 2009 ESC Guideline Change on Surgically Treated Infective Endocarditis.

BACKGROUND: In 2009, updated European Society of Cardiology guidelines on the prevention, diagnosis, and treatment of infective endocarditis (IE) were released and restricted the use of antibiotic prophylaxis to high-risk patients only. The aim of this study was to analyze the effect of the restrictive antibiotic regimen on the incidence and manifestations of surgically treated IE before and after the guideline change. METHODS: This study retrospectively analyzed data of 4917 patients who underwent valve surgical procedures for IE between 1994 and 2018 in 6 German cardiac surgery centers. Potential risk factors for 30-day mortality were assessed using logistic regression. Interrupted time series regression was used to evaluate the effect of the guideline change on the manifestation of IE. RESULTS: A total of 2014 patients (41%) underwent surgical procedures before the guideline change, and 2903 patients (59%) underwent surgical procedures after the change. After 2009, patients were older (67.0 years [interquartile range, 56.0-74.0 years] vs 64.0 years [interquartile range, 52.0-71.0 years]; P < .001), and they presented with more comorbidities, such as hypertension (56.9% vs 41.7%; P < .001), diabetes (27.4% vs 24.4%; P = .020), peripheral artery disease (8.5% vs 6.5%; P = .011), and preoperative acute kidney injury (42.8% vs 31.9%; P < .001). Patients had worse clinical outcomes with respect to 30-day mortality (18.1% vs 14.3%; P = .001) and 1-year mortality (37.1% vs 29.1%; P < .001). An increase in Streptococcus-related IE (P = .002) and an increase in mitral valve IE (P = .035) were observed after the guideline change. CONCLUSIONS: Since 2009, there has been a significant increase in the incidence of mitral valve IE and Streptococcus-related IE. Patients undergoing surgical procedures for IE present with more comorbidities, which contribute to high mortality rates.

Postcardiotomy Veno-Arterial Extracorporeal Membrane Oxygenation: Does the Cannulation Technique Influence the Outcome?

Objectives: Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) may be cannulated using either central (cannulation of aorta) or peripheral (cannulation of femoral or axillary artery) access. The ideal cannulation approach for postcardiotomy cardiogenic shock (PCS) is still unknown. The aim of this study is to compare the outcome of patients with PCS who were supported with central vs. peripheral cannulation. Methods: This is a single-center retrospective data analysis including all VA-ECMO implantations for PCS from January 2011 to December 2017. The central and peripheral approaches were compared in terms of patient characteristics, intensive care unit (ICU) stay, hospitalization length, adverse event rates, and overall survival. Results: Eighty-six patients met the inclusion criteria. Twenty-eight patients (33%) were cannulated using the central approach, and 58 patients (67%) were cannulated using the peripheral approach. Forty-three patients (50%) received VA-ECMO in the operating room and 43 patients (50%) received VA-ECMO in the ICU. Central VA-ECMO group had higher EuroSCORE II (p = 0.007), longer cross-clamp time (p = 0.054), higher rate of open chest after the procedure (p < 0.001), and higher mortality rate (p = 0.02). After propensity score matching, 20 patients in each group were reanalyzed. In the matched groups, no statistically significant differences were observed in the baseline characteristics between the two groups except for a higher rate of open chests in the central ECMO group (p = 0.02). However, no significant differences were observed in the outcome and complications between the groups. Conclusions: This study showed that in postcardiotomy patients requiring VA-ECMO support, similar complication rates and outcome were observed regardless of the cannulation strategy.

Surgical results for prosthetic versus native valve endocarditis: A multicenter analysis.

OBJECTIVES: Prosthetic valve endocarditis is associated with worse outcomes compared with native valve endocarditis. Our aim was to evaluate the impact of native valve endocarditis versus prosthetic valve endocarditis on postoperative outcomes and long-term survival and to identify preoperative risk factors in a large cohort of 4300 patients with infective endocarditis. METHODS: This retrospective cohort study was conducted in 5 German Cardiac Surgery Centers: the Clinical Multicenter Project of Analysis of Infective Endocarditis in Germany. Data of 4300 patients undergoing valve surgery for native valve endocarditis and prosthetic valve endocarditis were retrospectively analyzed. Univariable and multivariable analyses were used for risk stratification, Kaplan-Meier analysis for long-term survival. In addition, we performed Cox proportional hazards regression with multivariable adjustment. RESULTS: Between 1994 and 2016, 3143 patients (73.1%) underwent surgery for native valve endocarditis and 1157 patients (26.9%) underwent surgery for prosthetic valve endocarditis. Patients with prosthetic valve endocarditis were older (69 [60-75] vs 63 [52-72] years; P < .001) and had more comorbidities, such as hypertension (55% vs 46%; P < .001), diabetes (28% vs 25%; P = .020), coronary artery disease (32% vs 23%; P < .001), and preoperative acute kidney injury (41% vs 32%; P < .001). Kaplan-Meier analysis revealed significantly decreased long-term survival of patients undergoing surgery for prosthetic valve endocarditis compared with native valve endocarditis (P < .001). However, after multivariable adjustment, there was no significant difference in long-term survival between patients undergoing cardiac surgery with prosthetic valve endocarditis compared with native valve endocarditis. CONCLUSIONS: After adjusting for preoperative comorbidities, long-term survival for prosthetic valve endocarditis and native valve endocarditis is comparable. Thus, our large cohort study provides evidence that prosthetic valve endocarditis alone should not be a contraindication for redo operations.