Standardized angiographic projections allow evaluation of coronary artery side branches with quantitative flow ratio (QFR)

Quantitative flow ratio (QFR) is a novel, software-based noninvasive method for the quantitative evaluation of coronary physiology. QFR results correlate with invasive FFR measurements in the three main epicardial coronary arteries. However, QFR data for the evaluation of coronary side branches (SB) are scarce. The evaluation of QFR-performance of SB was retrospective and prospective. Eighty-seven patients with suspected chronic coronary syndrome, who received angiography using routine core lab projections, were retrospectively analyzed. On the second part 37 patients, who received angiography using recommended standardized coronary angiography projections, were prospectively analyzed. Quantitative analysis was performed for SB with a maximum lumen diameter proximal of ≥2 mm based on quantitative coronary angiography (QCA) by two certified experts with the software QAngio XA 3D 3.2. Using routine projections, QFR computation in 55 % of the SB were obtained (123 out of 224). Using standardized projections, 85 % of SB were computed by QFR (64 out of 75; p < 0.001 vs routine projections). The fluoroscopy time for recommended projections was not significantly different as opposed to routine projections (3.75 ± 2.2 vs. 4.58 ± 3.00 min, p = 2.6986). Using the standardized projections was associated with a higher amount of contrast medium (53.44 ± 24.23 vs. 87.95 ± 43.73 ml, p < 0.01), longer overall procedure time (23.23 ± 16.35 vs. 36.14 ± 17.21 min, p < 0.01) and a higher dose area product (1152.28 ± 576.70 vs. 2540.68 ± 1774.07 cGycm2, p < 0.01). Our study shows that the blood flow of the vast majority of coronary SB can be determined non-invasively by QFR in addition to the main epicardial coronary arteries when standardized projections are used.

Evaluation of coronary artery side branches (SB) with Quantitative Flow Ratio (QFR) by comparing the use of recommended angiographic projections with routine angiographic projections as Reference

Background

Contrast-flow quantitative flow ratio (QFR) is a novel, noninvasive method for the quantitative evaluation of coronary physiology using computational fluid dynamics based on 3D vessel reconstruction in angiograms. Computing this 3D-model with analyzing the dynamics of the contrast medium flow with a specialized algorithm, the software computes the virtual FFR. This new technique has shown a high accuracy in determining the functional significance of coronary stenosis of the three main epicardial coronary arteries using the gold standard FFR as reference. However, QFR data for the evaluation of coronary side branches (SB) are scarce. Therefore, the study aimed to determine the feasibility of this novel method to analyze SB and to characterize optimal viewing angles for evaluation using QFR.

Methods

A total of 87 patients, who underwent invasive coronary angiography with routine core lab projections, were enrolled in the study and were analyzed retrospectively by two certified experts with the software QAngio XA 3D 3.2. In addition, 37 patients were enrolled prospectively using coronary angiography projections recommended for the virtual QFR-Analysis. Quantitative Analysis was performed only for SB with a maximum lumen diameter (MLD) of ≥2mm. The following outcome parameters were analyzed: baseline characteristics, anatomical SB parameters such as MLD (mm) and vessel length (VL; mm) of the SB, result of the QFR-computation and procedure parameters, such as use of applicated contrast medium and fluoroscopy time.

Results

187 side branches (obtuse marginal [OM], diagonal branch [DB], intermediate artery [IA], posterolateral branch [PLB] and posterior descending artery [PDA]) were analyzed using QFR. Out of 87 patients undergoing an invasive coronary angiography with routine core lab projections with 244 SB ≥2mm, 123 SB (55%) were computable with the use of QFR. In the prospective cohort of 37 patients with recommended angiographic projections for QFR analysis of main branches, 75 SB ≥2mm were found. 64 of the 75 SB (84%) were computable with the use of QFR. The use of recommended projections led to an overall higher evaluability of SB (85% vs. 55%). The data show that the fluoroscopy time for recommended QFR projections was not significantly different as the time for routine cath lab projections (3.7±2.2 vs. 4.6±3, p=2.69). The study shows a significant increase of the amount of contrast medium used for QFR projections (55.4±24.2 vs. 87.9±43.7, p&lt;0.01).

Conclusion

To our knowledge this is the first study evaluating QFR for SB analysis. QFR is feasible for the routine assessment of side branches (SD) with MLD ≥2mm. The use of recommended projections significantly improved the quality of the QFR SB analysis apart from PDA, without increasing the fluoroscopy time during coronary angiography. Overall QFR could increase the use of physiologically guided coronary interventions, not only for the main epicardial vessels, but also for the SB.

Funding Acknowledgement

Type of funding sources: None.

Comparison of one-year survival prediction tools in patients with advanced heart failure

Background

Predicting survival in patients with advanced heart failure (HF) remains difficult and prognostic scores such as the Seattle Heart Failure Model (SHFM) are cumbersome to use. Alternative approaches like the Surprise Question (SC) or the number of HF hospitalisations within the last year (NoH) could simplify prognostication.

Purpose

We assessed the prognostic utility of the SHFM, SC and NoH for predicting one-year survival status in patients with advanced HF.

Methods

A secondary analysis of a multisite, single-blinded cluster-randomized, controlled trial to test whether a structured intervention of educational content and automated reminders increased the likelihood of ICD deactivation conversations and ICD deactivation. The study was performed within the advanced HF practices at six US academic medical centers, between September 2011 to February 2016. Patient eligibility criteria included advanced HF, an implantable cardiac defibrillator and a high risk of death, with complete data on SHFM, SC, NoH and one-year survival status. SHFM survival was calculated from baseline variables; the SC (“Would you be surprised if the patient were to die within one year?”) was answered by cardiologists; and the NoH was extracted from medical records. For prediction of survival status, cut-offs for predicted survival per SHFM and NoH were chosen empirically by means of receiver operating characteristic (ROC) curve analysis maximising Youden's index. The resulting binary prediction models were assessed based on area under the ROC curve (AUC), sensitivity and specificity.

Results

Of the 535 subjects in our sample, 82 (15.3%) had died after one-year of follow-up. For the SHFM and the NoH, optimal cut-offs were found to be a predicted survival &lt;86% and ≥2 hospitalisations, respectively.

Performance metrics of prognostic models are detailed in Table 1. The SHFM yielded an AUC of 0.65 (0.60–0.71 95% confidence interval [CI]), a sensitivity of 0.76 (0.65–0.84 95% CI), and a specificity of 0.55 (0.50–0.60 95% CI). The SC demonstrated a comparable AUC 0.58 (0.54–0.63 95% CI), similar sensitivity 0.84 (0.74–0.91 95% CI), but lower specificity 0.33 (0.28–0.37 95% CI) compared to the SHFM. The NoH demonstrated a comparable AUC 0.56 (0.50–0.62 95% CI), similar sensitivity 0.56 (0.45–0.67 95% CI), and similar specificity 0.56 (0.51–0.61 95% CI) compared to the SHFM. The combination of positive SC and NoH ≥2 showed significantly higher specificity compared to the SHFM (0.68 [0.64–0.73 95% CI]).

Conclusion

The SC and NoH are clinically feasible bedside alternatives to the more complex SHFM model, yet yield similar overall prognostic utility for one-year survival status among advanced HF patients.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): National Heart, Lung, and Blood Institute

Evaluation of Ti/Al alloy coated with biogenic hydroxyapatite as an implant device in dogs' femur bones

The main target of the present research was a full assessment of the toxicity effects and biocompatibility of a Ti/Al-alloy device coated with biogenic hydroxyapatite (bHA) when implanted in dogs in comparison with those of an uncoated Ti/Al-alloy device. The coating of the alloy was carried out using controlled high-velocity suspension flame spray (HVSFS) technique. Both coated and uncoated devices were implanted in dogs' femur bones for different time periods (45 days and 90 days). Bone-formation ability and healing were followed up, and blood analysis was performed, at Time zero (immediately post surgery), and then at 3 days, 45 days, and 90 days post surgery. Bone mineral density checks, radiological scans of the femur bone, and histological analysis were also conducted. The in-vivo study results proved that implantation of a device made from bHA-coated Ti/Al alloy in dogs' femur bones is completely safe. This is due to the high osteoconductivity of the coated alloy, which enables the formation of new bone and a full connection between new and original bone material. At 90 days post surgery, the coated alloy had been completely digested within the original bone; thus, it appeared as a part of the femur bone and not as a foreign body. Both the scanning electron microscopy with energy-dispersive X-ray and histology analysis findings affirmed the results. Furthermore, the blood tests indicated no toxicity effects during the 90 days of implantation.

[Current situation of allocation of academic medical personnel in ophthalmology departments in Germany]

BACKGROUND

At present minimum nursing staff numbers have been defined and are being implemented. In December 2019 the German Medical Association asked the German professional associations about their general experience with planning of medical personnel in hospital departments. As no structured data were available on this subject, the German Ophthalmological Society (DOG) founded a working group in March 2020 to answer this request.

METHOD

In the course of several consensus meetings, the working group on personnel planning for physicians in hospitals of the DOG prepared a questionnaire on previous experiences in personnel planning of eye hospitals, which was sent to the heads of all university eye hospitals and departments of ophthalmology in Germany. The questionnaire consisted of individual items with fixed choices and free answers regarding the procedure and current situation of staffing as well as the range of tasks and organization of the medical service.

RESULTS

Out of 104 departments 53 (51%) responded, of which 25 were from university departments (64% response), 23 from departments of other public or non-profit ownership (46%) and 5 from departments with private hospital ownership (33%). Of these 49% stated that there was no transparent basis for calculation of the number of medical positions in their hospital. Of the surveyed departments, outpatient tasks, services and revenues were considered in the calculations in only 47%. There was a statistically significant higher ratio of full-time personnel to the numbers of beds in university departments compared to private and publicly owned non-profit institutions (p < 0.001, t‑test). All departments have to cope with multiple additional tasks in addition to clinical patient care, which are taken into account only to a limited extent in the staffing. Approximately 70% of the departments provide a 24 h/7 day (24/7) medical on-call service on site, 91% have a 24/7 surgery on-call service and 34% have a cooperation with emergency services run by the Association of Statutory Health Insurance Physicians.

CONCLUSION

The results show how heterogeneously and nontransparent German departments of ophthalmology are staffed in terms of medical doctors. On average, university departments have higher personnel resources per hospital bed to cope with additional tasks in research and teaching. Outpatient tasks, which contribute significantly to the revenues of an eye department, and multiple other tasks are often not taken into account in the personnel calculation. A transparent and uniform basis for calculation of the medical staff of the departments is desirable in order to achieve a sufficient personnel staffing for a patient and employee-oriented working environment.

Human lipoxygenase isoforms form complex patterns of double and triple oxygenated compounds from eicosapentaenoic acid

Lipoxygenases (ALOX) are lipid peroxidizing enzymes that catalyze the biosynthesis of pro- and anti-inflammatory lipid mediators and have been implicated in (patho-)physiological processes. In humans, six functional ALOX isoforms exist and their arachidonic acid oxygenation products have been characterized. Products include leukotrienes and lipoxins which are involved in the regulation of inflammation and resolution. Oxygenation of n3-polyunsaturated fatty acids gives rise to specialized pro-resolving mediators, e.g. resolvins. However, the catalytic activity of different ALOX isoforms can lead to a multitude of potentially bioactive products. Here, we characterized the patterns of oxygenation products formed by human recombinant ALOX5, ALOX15, ALOX15B and ALOX12 from eicosapentaenoic acid (EPA) and its 18-hydroxy derivative 18-HEPE with particular emphasis on double and triple oxygenation products. ALOX15 and ALOX5 formed a complex mixture of various double oxygenation products from EPA, which include 5,15-diHEPE and various 8,15-diHEPE isomers. Their biosynthetic mechanisms were explored using heavy oxygen isotopes (H₂¹⁸O, ¹⁸O₂ gas) and three catalytic activities contributed to product formation: i) fatty acid oxygenase activity, ii) leukotriene synthase activity, iii) lipohydroperoxidase activity. For ALOX15B and ALOX12 more specific product patterns were identified, which was also the case when these enzymes reacted in concert with ALOX5. Several double oxygenated compounds were formed from 18-HEPE by ALOX5, ALOX15B and ALOX12 including previously identified resolvins (RvE2, RvE3), while formation of triple oxygenation products, e.g. 5,17,18-triHEPE, required ALOX5. Taken together our data show that EPA can be converted by human ALOX isoforms to a large number of secondary oxygenation products, which might exhibit bioactivity.

Angiography-based quantitative coronary contrast-flow ratio measurements correlate with myocardial ischemia assessed by stress MRI

Contrast-flow quantitative flow ratio (cQFR) is a new technology for quantitative evaluation of coronary stenosis using computational fluid dynamics based on angiograms. The aim of this study was to assess the sensitivity and specificity of cQFR to detect myocardial ischemia using stress magnetic resonance imaging (MRI) as a reference standard. Patients who received stress MRI and coronary angiography were selected from the hospital database. Relevant ischemia on stress MRI was defined as a perfusion deficit in ≥ 2 of 16 segments. cQFR was quantitated based on 3-dimensional quantitative coronary angiography using QAngio XA3D1.1 software by two blinded and independent investigators. A cQFR of ≤ 0.80 was considered abnormal. Among 87 patients 230 vessels met the criteria for full analysis by cQFR (88%). In vascular territories with a significant perfusion deficit, cQFR was significantly lower compared to areas with normal perfusion (0.72 (0.62–0.78) vs. 0.96 (0.89–0.99); p < 0.001). The sensitivity of cQFR in detecting significant epicardial stenoses of coronary vessels with documented ischemia in stress MRI was 81% (68–90%), the specificity was 88% (82–92%). Diameter stenoses (DS) and area stenoses (AS) in vessels with positive stress MRI were significantly higher than in vessels without ischemia (DS 59.1% (49.4–68.4%) vs. 34.8% (27.1–46.1%) p < 0.001; AS 75.6% (63.0–85.2%) vs. 45.0% (30.8–63.6%), p < 0.001). The analysis reveals a high correlation between coronary stenosis measured by cQFR and ischemic areas detected by stress MRI. The data set the stage to plan randomized studies assessing cQFR measurements with regard to clinical outcomes.

A synthetic epoxyeicosatrienoic acid analogue prevents the initiation of ischemic acute kidney injury

AIM

Imbalances in cytochrome P450 (CYP)-dependent eicosanoid formation may play a central role in ischemic acute kidney injury (AKI). We reported previously that inhibition of 20-hydroxyeicosatetraenoic acid (20-HETE) action ameliorated ischemia/reperfusion (I/R)-induced AKI in rats. Now we tested the hypothesis that enhancement of epoxyeicosatrienoic acid (EET) actions may counteract the detrimental effects of 20-HETE and prevent the initiation of AKI.

METHODS

Male Lewis rats underwent right nephrectomy and ischemia was induced by 45 min clamping of the left renal pedicle followed by up to 48 h of reperfusion. Circulating CYP-eicosanoid profiles were compared in patients who underwent cardiac surgery with (n = 21) and without (n = 38) developing postoperative AKI.

RESULTS

Ischemia induced an about eightfold increase of renal 20-HETE levels, whereas free EETs were not accumulated. To compensate for this imbalance, a synthetic 14,15-EET analogue was administered by intrarenal infusion before ischemia. The EET analogue improved renal reoxygenation as monitored by in vivo parametric MRI during the initial 2 h reperfusion phase. The EET analogue improved PI3K- as well as mTORC2-dependent rephosphorylation of Akt, induced inactivation of GSK-3β, reduced the development of tubular apoptosis and attenuated inflammatory cell infiltration. The EET analogue also significantly alleviated the I/R-induced drop in creatinine clearance. Patients developing postoperative AKI featured increased preoperative 20-HETE and 8,9-EET levels.

CONCLUSIONS

Pharmacological interventions targeting the CYP-eicosanoid pathway could offer promising new options for AKI prevention. Individual differences in CYP-eicosanoid formation may contribute to the risk of developing AKI in clinical settings.

P1760Incidence and effects of stroke, MI and bleeding on mortality among patients with ACS undergoing PCI: a comparative analysis from the PROMETHEUS registry

Background

Stroke represents a potentially calamitous complication among patients with acute coronary syndrome (ACS) undergoing percutaneous coronary intervention (PCI) even though its rates are relatively low. Data on the distribution of stroke occurrence over time and its overlap with myocardial infarction (MI) and bleeding after PCI is scarce.

Purpose

We sought to compare the occurrence and impacts of stroke, MI and bleeding on subsequent mortality in ACS patients undergoing PCI in contemporary clinical practice.

Methods

A total of 19,914 ACS patients who underwent PCI in the PROMETHEUS multi-center observational study were analyzed. We calculated the cumulative stroke incidence at 30 days and 1 year using Kaplan Meier (KM) method. We also compared the distribution of stroke, myocardial infarction (MI) and bleeding across time and evaluated the overlap between their occurrences. Predictors of 1 year stroke occurrence were identified through multivariable Cox-regression and stroke, MI and bleeding were entered as time-updated covariates to estimate their individual effects on subsequent mortality.

Results

Of the total number of patients, 244 patients (1.5%) had a stroke within 1 year. 48 of these patients also experienced an MI while another 48 patients experienced a bleeding event. Furthermore, 14 of these overlapping patients experienced a stroke, MI and bleeding event, all within the 1-year follow-up. Patients who sustained a stroke were more likely to have a prior history of cerebrovascular disease, peripheral artery disease, MI and heart failure compared to those who did not have a stroke. Mortality risk was significantly higher among those with stroke versus those without stroke (adjusted HR 4.84, p<0.0001). However, the association attenuated over time with a much larger effect in the first 30 days of its occurrence (adjusted HR 17.7, p<0.0001) versus beyond 30 days (adjusted HR 1.22; 95% CI: 0.6–2.46, p=0.58). Although the effects of MI and bleeding on subsequent mortality within 30 days of occurrence were significantly lower than stroke (adjusted HR 6.22, p<0.0001; adjusted HR 7.30, p<0.0001, respectively), their effects were more sustained on mortality beyond 30 days (adjusted HR 2.89, p<0.0001; adjusted HR 3.05, p<0.0001, respectively).

Conclusion

When compared with MI and bleeding, stroke had a substantially stronger impact on mortality that attenuated rapidly over time among ACS patients undergoing PCI. Optimization of modifiable risk factors and medication adherence are essential parts of management of stroke following PCI for ACS.

P2701Comparison of myocardial ischemia assessed by contrast-flow quantitative flow ratio (cQFR) and by stress MRI in patients with stable coronary artery disease

Background

Contrast-flow quantitative flow ratio (cQFR) is a new technology for evaluation of coronary stenosis. cQFR allows to derive the fractional flow reserve (FFR) from coronary angiograms. Based on a three dimensional coronary model, FFR is calculated from computational fluid dynamics. Head to head comparisons with FFR showed an overall diagnostic accuracy of 85%. cQFR does not require coronary wires or hyperemia. However, the ability of cQFR to detect myocardial ischemia is unknown. Therefore, the aim of this study was to evaluate the relationship between cQFR and myocardial ischemia assessed by stress magnetic resonance imaging (stress MRI).

Methods

cQFR analysis was performed in patients selected from the hospital database who received stress MRI and coronary angiography. A relevant ischemia on stressMRI was defined as a perfusion deficit in ≥2 of 16 segments. The cQFR was based on 3-dimensional quantitative coronary angiography (3D-QCA) using the QAngio XA 3D 1.1, Medis Medical Imaging System, Leiden, The Netherlands. Two blinded investigators analysed all 3 main coronary vessels of each patient measuring diameter stenosis (DS), area stenosis (AS) and cQFR. A cQFR of ≤0.8 was considered abnormal. The primary endpoint was sensitivity and specificity of cQFR using stress MRI as a reference standard.

Results

125 vessels of 53 patients could be fully analysed by cQFR (78.6%). The sensitivity of cQFR in detecting significant epicardial stenoses of coronary vessels with documented ischemia in stress MRI was 75%, the specificity was 87%. The 3D-QCA-derived diameter stenoses and area stenoses in vessels with positive stress MRI were significantly higher than in vessels without ischemia (see Table 1).

Table 1. Means of diameter stenosis (DS) und area stenosis (AS) with interquartile range (IQR) Total (n=125) Ischemia (n=32) No Ischemia (n=93) p-value DS [%] 42.3 (28.3–53.1) 57.1 (47–68.5) 37.7 (27.6–45.1) <0.0001 AS [%] 51.8 (32.4–69.7) 68.9 (56.8–85.9) 46.5 (29.7–62.7) <0.0001

Conclusion

The analysis reveals a high correlation between relevant coronary stenosis measured by cQFR and ischemic areas detected by stress MRI. Differences between the two methods are plausible because stress MRI detects ischemia due to other reasons than epicardial stenosis. Further randomized studies are mandatory to verify the prognostic significance of the cQFR measurements.

Local electronic structure of the peptide bond probed by resonant inelastic soft X-ray scattering

Soft X-ray emission spectroscopy and RIXS are used to determine the local electronic structure of the peptide bond.

Functional characterization of a novel arachidonic acid 12S-lipoxygenase in the halotolerant bacterium Myxococcus fulvus exhibiting complex social living patterns

Lipoxygenases are lipid peroxidizing enzymes, which frequently occur in higher plants and mammals. These enzymes are also expressed in lower multicellular organisms but here they are not widely distributed. In bacteria, lipoxygenases rarely occur and evaluation of the currently available bacterial genomes suggested that <0.5% of all sequenced bacterial species carry putative lipoxygenase genes. We recently rescreened the public bacterial genome databases for lipoxygenase-like sequences and identified two novel lipoxygenase isoforms (MF-LOX1 and MF-LOX2) in the halotolerant Myxococcus fulvus. Both enzymes share a low degree of amino acid conservation with well-characterized eukaryotic lipoxygenase isoforms but they involve the catalytically essential iron cluster. Here, we cloned the MF-LOX1 cDNA, expressed the corresponding enzyme as N-terminal hexa-his-tag fusion protein, purified the recombinant enzyme to electrophoretic homogeneity, and characterized it with respect to its protein-chemical and enzymatic properties. We found that M. fulvus expresses a catalytically active intracellular lipoxygenase that converts arachidonic acid and other polyunsaturated fatty acids enantioselectively to the corresponding n-9 hydroperoxy derivatives. The enzyme prefers C₂₀ - and C₂₂ -polyenoic fatty acids but does not exhibit significant membrane oxygenase activity. The possible biological relevance of MF-LOX1 will be discussed in the context of the suggested concepts of other bacterial lipoxygenases.

Chiral lipidomics of monoepoxy and monohydroxy metabolites derived from long-chain polyunsaturated fatty acids

A chiral lipidomics approach was established for comprehensive profiling of regio- and stereoisomeric monoepoxy and monohydroxy metabolites of long-chain PUFAs as generated enzymatically by cytochromes P450 (CYPs), lipoxygenases (LOXs), and cyclooxygenases (COXs) and, in part, also unspecific oxidations. The method relies on reversed-phase chiral-LC coupled with ESI/MS/MS. Applications revealed partially opposing enantioselectivities of soluble and microsomal epoxide hydrolases (mEHs). Ablation of the soluble epoxide hydrolase (sEH) gene resulted in specific alterations in the enantiomeric composition of endogenous monoepoxy metabolites. For example, the (R,S)/(S,R)-ratio of circulating 14,15-EET changed from 2.1:1 in WT to 9.7:1 in the sEH-KO mice. Studies with liver microsomes suggested that CYP/mEH interactions play a primary role in determining the enantiomeric composition of monoepoxy metabolites during their generation and release from the ER. Analysis of human plasma showed significant enantiomeric excess with several monoepoxy metabolites. Monohydroxy metabolites were generally present as racemates; however, Ca²⁺-ionophore stimulation of whole blood samples resulted in enantioselective increases of LOX-derived metabolites (12S-HETE and 17S-hydroxydocosahexaenoic acid) and COX-derived metabolites (11R-HETE). Our chiral approach may provide novel opportunities for investigating the role of bioactive lipid mediators that generally exert their physiological functions in a highly regio- and stereospecific manner.

Synthesis, spectroscopic characterisation and transmetalation of lithium and potassium diaminophosphanide-boranes

A secondary diaminophosphane-borane (Et₂N)₂PH(BH₃) was prepared from a chlorophosphane precursor and LiBH₄ and metalated by reaction with anion bases (n-BuLi, KN(SiMe₃)₂) to yield the corresponding metal diaminophosphanide-boranes [(Et₂N)₂P(BH₃)]M (M = Li, K). Multinuclear NMR studies permitted the first spectroscopic characterisation of the metalation products and revealed the presence of monomeric (for M = Li) contact ion pairs in solution. NMR spectroscopic evidence that the ions in each pair interact via LiP- rather than LiH₃B-interactions as had been inferred for a Ph-substituted analogue was confirmed by DFT studies, which revealed also that the borane coordination plays a decisive role in boosting the PH-acidity of the original secondary diaminophosphane precursor. Transmetalation of the potassium and lithium diaminophosphanide-boranes with Cu(i) and Zn(ii) chlorides afforded the first functional transition metal complexes of a P-heteroatom-functionalised phosphanide-borane ligand. Both products were fully characterised. Thermolysis of the Cu-complex induced a reaction which involved transfer of an NHC ligand from the metal to the phosphorus atom and yielded a phosphaalkene NHC[double bond, length as m-dash]PH (NHC = N-heterocyclic carbene) as the major phosphorus-containing product.

Myogenic Response Reduction by High Blood Glucose Levels in Human Retinal Arterioles

PURPOSE

The effect of elevated blood glucose level on the myogenic response of human retinal arterioles to acute increases in blood pressure is investigated.

METHODS

The vascular response to raised blood pressure (Bayliss effect) was measured in 12 healthy volunteers by use of the retinal vessel analyzer (RVA). For a 9-minute period an on-line measurement of the diameter of a retinal branch arteriole was performed. After the first 3 minutes (baseline measurement) a second phase with 3 minutes of isometric exercise caused an acute rise in blood pressure, followed by 3 minutes of recovery (phase III). After the first session 100 g glucose were administered per os. After 30 minutes blood glucose was measured again and an identical second session was performed with higher blood glucose levels. The Wilcoxon test was used for statistical analysis.

RESULTS

During the first session a rise in mean arterial pressure of 22.8 (+/-8.4) mmHg was followed by an arterial vasoconstriction of -6.6 (+/-1.7) %. The administration of 100 g glucose resulted in a significant rise in blood glucose levels within 30 minutes between the two sessions (4.35 mmol/L vs 7.46 mmol/L) (p=0.002). The blood pressure rise of 25.7 (+/-7.3) mm Hg in the second session was associated with a significant loss in arterial vasoconstriction of -2.3 (+/-1.4) % (session I vs session II p=0.002).

CONCLUSIONS

The myogenic response of the arterial wall in human retinal arterioles was significantly reduced during acute rise of blood glucose levels.

Site-specific electronic structure of imidazole and imidazolium in aqueous solutions

The electronic structures of aqueous imidazole and imidazolium solutions are studied in an atom- and site-specific fashion using soft X-ray spectroscopy.

Hypoxia-reoxygenation enhances murine afferent arteriolar vasoconstriction by angiotensin II

We tested the hypothesis that hypoxia-reoxygenation (H/R) augments vasoreactivity to angiotensin II (ANG II). In particular, we compared an in situ live kidney slice model with isolated afferent arterioles (C57Bl6 mice) to assess the impact of tubules on microvessel response. Hematoxylin and eosin staining was used to estimate slice viability. Arterioles in the slices were located by differential interference contrast microscopy, and responses to vasoactive substances were assessed. Cytosolic calcium transients and NADPH oxidase (NOX) mRNA expression were studied in isolated afferent arterioles. SOD activity was measured in live slices. Both experimental models were subjected to control and H/R treatment (60 min). Slices were further analyzed after 30-, 60-, and 90-min hypoxia followed by 10- or 20-min reoxygenation (H/R). H/R resulted in enhanced necrotic tissue damage compared with control conditions. To characterize the slice model, we applied ANG II (10^-7 M), norepinephrine (NE; 10^-5 M), endothelin-1 (ET-1; 10^-7 M), and ATP (10^-4 M), reducing the initial diameter to 44.5 ± 2.8, 50.0 ± 2.2, 45.3 ± 2.6, and 74.1 ± 1.8%, respectively. H/R significantly increased the ANG II response compared with control in live slices and in isolated afferent arterioles, although calcium transients remained similar. TEMPOL incubation prevented the H/R effect on ANG II responses. H/R significantly increased NOX2 mRNA expression in isolated arterioles. SOD activity was significantly decreased after H/R. Enhanced arteriolar responses after H/R occurred independently from the surrounding tissue, indicating no influence of tubules on vascular function in this model. The mechanism of increased ANG II response after H/R might be increased oxidative stress and increased calcium sensitivity of the contractile apparatus.

[Refractive lenticule extraction - The ReLEx/SMILE technique : Video article]

Refractive lenticule extraction (ReLEx/SMILE) is a refractive surgical method developed by the authors in stages primarily for correction of myopia and myopic astigmatism, in which a femtosecond laser is exclusively used. In the (ReLEx/SMILE) method a refractive lenticule is generated by the femtosecond laser, which is subsequently extracted through a small incision. Opening of the corneal surface with a flap and use of an excimer laser is no longer necessary. In 2013 the method was newly assessed and classified by the Joint Commisssion for Refractive Surgery (KRC) of the Professional Association of Ophthalmologists (BVA) and the German Ophthalmological Society (DOG). This article presents the individual stages of the technique in a video and possible errors and their avoidance are explained.

[Flexible Guidance of Ultra-Short Laser Pulses in Ophthalmic Therapy Systems]

In the last 20 years, the role of ultrashort pulsed lasers in ophthalmology has become increasingly important. However, it is still impossible to guide ultra-short laser pulses with standard glass fibres. The highly energetic femtosecond pulses would destroy the fibre material, and non-linear dispersion effects would significantly change beam parameters. In contrast, photonic crystal fibres mainly guide the laser pulses in air, so that absorption and dispersive pulse broadening have essentially no effect. This article compares classical beam guidance with mirrors, lenses and prisms with photonic crystal fibres and describes the underlying concepts and the current state of technology. A classical mirror arm possesses more variable optical properties, while the HCF (Hollow-Core Photonic Crystal Fibre) must be matched in terms of the laser energy and the laser spectrum. In contrast, the HCF has more advantages in respect of handling, system integration and costs. For applications based on photodisruptive laser-tissue interaction, the relatively low damage threshold of photonic crystal fibres compared to classic beam guiding systems is unacceptable. If, however, pulsed laser radiation has a sufficiently low peak intensity, e.g. as used for plasma-induced ablation, photonic crystal fibres can definitely be considered as an alternative solution to classic beam guidance.

[Historical Overview of the Clinical Development of the Small Incision Lenticule Extraction Surgery (SMILE)]

The clinical use of femtosecond lasers has led to significant progress in the quality of refractive surgery. SMILE femtosecond laser surgery (SMILE: Small Incision Lenticule Extraction) permits the first one step intrastromal laser procedure without a flap. This article describes the gradual development of this surgery during the last ten years.

Vasopressin lowers renal epoxyeicosatrienoic acid levels by activating soluble epoxide hydrolase

Activation of the thick ascending limb (TAL) Na⁺-K⁺-2Cl^- cotransporter (NKCC2) by the antidiuretic hormone arginine vasopressin (AVP) is an essential mechanism of renal urine concentration and contributes to extracellular fluid and electrolyte homeostasis. AVP effects in the kidney are modulated by locally and/or by systemically produced epoxyeicosatrienoic acid derivates (EET). The relation between AVP and EET metabolism has not been determined. Here, we show that chronic treatment of AVP-deficient Brattleboro rats with the AVP V2 receptor analog desmopressin (dDAVP; 5 ng/h, 3 days) significantly lowered renal EET levels (-56 ± 3% for 5,6-EET, -50 ± 3.4% for 11,12-EET, and -60 ± 3.7% for 14,15-EET). The abundance of the principal EET-degrading enzyme soluble epoxide hydrolase (sEH) was increased at the mRNA (+160 ± 37%) and protein levels (+120 ± 26%). Immunohistochemistry revealed dDAVP-mediated induction of sEH in connecting tubules and cortical and medullary collecting ducts, suggesting a role of these segments in the regulation of local interstitial EET signals. Incubation of murine kidney cell suspensions with 1 μM 14,15-EET for 30 min reduced phosphorylation of NKCC2 at the AVP-sensitive threonine residues T96 and T101 (-66 ± 5%; P < 0.05), while 14,15-DHET had no effect. Concomitantly, isolated perfused cortical thick ascending limb pretreated with 14,15-EET showed a 30% lower transport current under high and a 70% lower transport current under low symmetric chloride concentrations. In summary, we have shown that activation of AVP signaling stimulates renal sEH biosynthesis and enzyme activity. The resulting reduction of EET tissue levels may be instrumental for increased NKCC2 transport activity during AVP-induced antidiuresis.

Investigation of the Ionic Hydration in Aqueous Salt Solutions by Soft X-ray Emission Spectroscopy

Understanding the molecular structure of the hydration shells and their impact on the hydrogen bond (HB) network of water in aqueous salt solutions is a fundamentally important and technically relevant question. In the present work, such hydration effects were studied for a series of representative salt solutions (NaCl, KCl, CaCl2, MgCl2, and KBr) by soft X-ray emission spectroscopy (XES) and resonant inelastic soft X-ray scattering (RIXS). The oxygen K-edge XES spectra could be described with three components, attributed to initial state HB configurations in pure water, water molecules that have undergone an ultrafast dissociation initiated by the X-ray excitation, and water molecules in contact with salt ions. The behavior of the individual components, as well as the spectral shape of the latter component, has been analyzed in detail. In view of the role of ions in such effects as protein denaturation (i.e., the Hofmeister series), we discuss the ion-specific nature of the hydration shells and find that the results point to a predominant role of anions as compared to cations. Furthermore, we observe a concentration-dependent suppression of ultrafast dissociation in all salt solutions, associated with a significant distortion of intact HB configurations of water molecules facilitating such a dissociation.

On the energetics of P–P bond dissociation of sterically strained tetraamino-diphosphanes

Thermochemical data for the homolytic P–P bond fission in tetraaminodiphosphanes (R₂N)₂P–P(NR₂)₂ were determined experimentally and computationally. The results confirm that radical formation is favoured by entropic and structural relaxation effects, and disfavoured by dispersion forces. Unlike aminophosphenium cations, the radicals display no strong preference for a planar (R₂N)₂P unit.

[Investigation of color vision in acute unilateral optic neuritis using a web-based color vision test]

BACKGROUND

In acute unilateral optic neuritis (ON) color vision defects combined with a decrease in visual acuity and contrast sensitivity frequently occur. This study investigated whether a web-based color vision test is a reliable detector of acquired color vision defects in ON and, if so, which charts are particularly suitable.

METHODS

In 12 patients with acute unilateral ON, a web-based color vision test ( www.farbsehtest.de ) with 25 color plates (16 Velhagen/Broschmann and 9 Ishihara color plates) was performed. For each patient the affected eye was tested first and then the unaffected eye.

RESULTS

The mean best-corrected distance visual acuity (BCDVA) in the ON eye was 0.36 ± 0.20 and 1.0 ± 0.1 in the contralateral eye. The number of incorrectly read plates correlated with the visual acuity. For the ON eye a total of 134 plates were correctly identified and 166 plates were incorrectly identified, while for the disease-free fellow eye, 276 plates were correctly identified and 24 plates were incorrectly identified. Both of the blue/yellow plates were identified correctly 14 times and incorrectly 10 times using the ON eye and exclusively correctly (24 times) using the fellow eye. The Velhagen/Broschmann plates were incorrectly identified significantly more frequently in comparison with the Ishihara plates. In 4 out of 16 Velhagen/Broschmann plates and 5 out of 9 Ishihara plates, no statistically significant differences between the ON eye and the fellow eye could be detected.

CONCLUSION

The number of incorrectly identified plates correlated with a decrease in visual acuity. Red/green and blue/yellow plates were incorrectly identified significantly more frequently with the ON eye, while the Velhagen/Broschmann color plates were incorrectly identified significantly more frequently than the Ishihara color plates. Thus, under defined test conditions the web-based color vision test can also be used to detect acquired color vision defects, such as those caused by ON. Optimization of the test by altering the combination of plates may be a useful next step.

Probing hydrogen bonding orbitals: resonant inelastic soft X-ray scattering of aqueous NH3

Resonant inelastic soft X-ray scattering was used to probe the hydrogen bonding orbitals in aqueous ammonia.

[One-year results of small incision lenticule extraction (SMILE) in myopia]

BACKGROUND

This clinical trial is focused on the 12-month results of a new method for refractive correction in myopia, called "small incision lenticule extraction" (SMILE).

PATIENTS AND METHODS

In a prospective study 91 eyes were treated with the new refractive procedure and the results were published after 6 months. A lenticule of intrastromal corneal tissue is cut utilising the Carl Zeiss Meditec AG (Jena, Germany) VisuMax femtosecond laser system. Thereafter, this lenticule is manually removed without lifting a flap. 55 eyes of 33 patients volunteered for a 12-month follow-up. UCVA and BSCVA after 12 months, objective and manifest refraction as well as slit-lamp examination and late side effects were documented.

RESULTS

55 eyes of 33 patients were re-examined in this study 12 months after surgery. The spherical equivalent before surgery was - 4.66 (± 1.75) D; after 12 months - 0.11 (± 0.42) D was manifest. No significant change was observed compared to the 6-month control. Starting with UCVA of 0.1 (± 0.06) before surgery. UCVA was 1.02 (± 0.3) after 12 months. One eye lost more than two lines. All other patients did not have any late side effects.

CONCLUSION

The one-year results of this new procedure are encouraging. Especially stability of the correction of myopia and myopic astigmatism with the SMILE procedure is very good.

[Morphological analysis of corneal refractive lenticules--is there a correlation with refractive results?]

BACKGROUND

ReLEx®flex is a corneal refractive procedure performed by removing corneal lenticules with a femtosecond (fs) laser system. Using electron microscopy, tissue parameters of extracted lenticules were analysed for potential correlations to the refractive results. Furthermore, the effect of previous contact lens (CL) wear on refractive stability (regression) was tested.

PATIENTS AND METHODS

19 lenticules from 11 patients (age 24-56 years, 8 f, 3 m) were prepared for EM. The central areas of the samples were photographed and the distance between the collagen fibres and their diameters were digitally measured. ANOVA analysis was used to correlate postoperative refractional stability with time of preoperative CL use, fibre diameter and the coefficient of variation (CV) of fibre distance.

RESULTS

14 of 19 lenticules were from patients who had worn CL preoperatively. The cumulative duration of CL wear averaged around 31.2 ± 35.5 thousand hours. Preoperative CL use significantly influenced the postoperative regression: the longer time patients had worn CL, the greater was the regression towards myopia (p = 0.01). Additionally, the morphological parameters collagen fibre diameter (p = 0.09) and CV of fibre distance (p = 0.07) had an impact on regression.

CONCLUSIONS

Prolonged CL use and alterations in ultrastructural patterns affected the refractive stability after ReLExflex. Although the pathophysiological relationships between CL use, corneal morphological parameters, and refractive stability are still poorly understood, these findings could potentially be used as prognostic markers for postoperative refraction after ReLExflex.

Setup for in situ investigation of gases and gas/solid interfaces by soft x-ray emission and absorption spectroscopy

We present a novel gas cell designed to study the electronic structure of gases and gas/solid interfaces using soft x-ray emission and absorption spectroscopies. In this cell, the sample gas is separated from the vacuum of the analysis chamber by a thin window membrane, allowing in situ measurements under atmospheric pressure. The temperature of the gas can be regulated from room temperature up to approximately 600 °C. To avoid beam damage, a constant mass flow can be maintained to continuously refresh the gaseous sample. Furthermore, the gas cell provides space for solid-state samples, allowing to study the gas/solid interface for surface catalytic reactions at elevated temperatures. To demonstrate the capabilities of the cell, we have investigated a TiO2 sample behind a mixture of N2 and He gas at atmospheric pressure.

Provision of long-acting reversible contraception in HIV-prevalent countries: results from nationally representative surveys in southern Africa

OBJECTIVE

To analyse the current provision of long-acting reversible contraception (LARC) and clinician training needs in HIV-prevalent settings.

DESIGN

Nationally representative survey of clinicians.

SETTING

HIV-prevalent settings in South Africa and Zimbabwe.

POPULATION

Clinicians in South Africa and Zimbabwe.

METHODS

Nationally representative surveys of clinicians were conducted in South Africa and Zimbabwe (n = 1444) to assess current clinical practice in the provision of LARC in HIV-prevalent settings. Multivariable logistic regression was used to analyse contraceptive provision and clinician training needs.

MAIN OUTCOME MEASURE

Multivariable logistic regression of contraceptive provision and clinician training needs.

RESULTS

Provision of the most effective reversible contraceptives is limited: only 14% of clinicians provide copper intrauterine devices (IUDs), 4% levonorgestrel-releasing IUDs and 16% contraceptive implants. Clinicians' perceptions of patient eligibility for IUD use were overly restrictive, especially related to HIV risks. Less than 5% reported that IUDs were appropriate for women at high risk of HIV or for HIV-positive women, contrary to evidence-based guidelines. Only 15% viewed implants as appropriate for women at risk of HIV. Most clinicians (82%), however, felt that IUDs were underused by patients, and over half desired additional training on LARC methods. Logistic regression analysis showed that LARC provision was largely restricted to physicians, hospital settings and urban areas. Results also showed that clinicians in rural areas and clinics, including nurses, were especially interested in training.

CONCLUSIONS

Clinician competency in LARC provision is important in southern Africa, given the low use of methods and high rates of unintended pregnancy among HIV-positive and at-risk women. Despite low provision, clinician interest is high, suggesting the need for increased evidence-based training in LARC to reduce unintended pregnancy and associated morbidities.

Novel signalling mechanisms and targets in renal ischaemia and reperfusion injury

Acute kidney injury (AKI) induced by ischaemia and reperfusion (I/R) injury is a common and severe clinical problem. Vascular dysfunction, immune system activation and tubular epithelial cell injury contribute to functional and structural deterioration. The search for novel therapeutic interventions for I/R-induced AKI is a dynamic area of experimental research. Pharmacological targeting of injury mediators and corresponding intracellular signalling in endothelial cells, inflammatory cells and the injured tubular epithelium could provide new opportunities yet may also pose great translational challenge. Here, we focus on signalling mediators, their receptors and intracellular signalling pathways which bear potential to abrogate cellular processes involved in the pathogenesis of I/R-induced AKI. Sphingosine 1 phosphate (S1P) and its respective receptors, cytochrome P450 (CYP450)-dependent vasoactive eicosanoids, NF-κB- and protein kinase-C (PKC)-related pathways are representatives of such 'druggable' pleiotropic targets. For example, pharmacological agents targeting S1P and PKC isoforms are already in clinical use for treatment for autoimmune diseases and were previously subject of clinical trials in kidney transplantation where I/R-induced AKI occurs as a common complication. We summarize recent in vitro and in vivo experimental studies using pharmacological and genomic targeting and highlight some of the challenges to clinical application of these advances.