Comparing x-ray phase-contrast imaging using a Talbot array illuminator to propagation-based imaging for non-homogeneous biomedical samples

Phase-contrast computed tomography can visualize soft tissue samples with high contrast. At coherent sources, propagation-based imaging (PBI) techniques are among the most common, as they are easy to implement and produce high-resolution images. Their downside is a low degree of quantitative data due to simplifying assumptions of the sample properties in the reconstruction. These assumptions can be avoided, by using quantitative phase-contrast techniques as an alternative. However, these often compromise spatial resolution and require complicated setups. In order to overcome this limitation, we designed and constructed a new imaging setup using a 2D Talbot array illuminator as a wavefront marker and speckle-based imaging phase-retrieval techniques. We developed a post-processing chain that can compensate for wavefront marker drifts and that improves the overall sensitivity. By comparing two measurements of biomedical samples, we demonstrate that the spatial resolution of our setup is comparable to the one of PBI scans while being able to successfully image a sample that breaks the typical homogeneity assumption used in PBI.

Three-dimensional analyses of vascular network morphology in a murine lymph node by X-ray phase-contrast tomography with a 2D Talbot array

With growing molecular evidence for correlations between spatial arrangement of blood vasculature and fundamental immunological functions, carried out in distinct compartments of the subdivided lymph node, there is an urgent need for three-dimensional models that can link these aspects. We reconstructed such models at a 1.84 µm resolution by the means of X-ray phase-contrast imaging with a 2D Talbot array in a short time without any staining. In addition reconstructions are verified in immunohistochemistry staining as well as in ultrastructural analyses. While conventional illustrations of mammalian lymph nodes depict the hilus as a definite point of blood and lymphatic vessel entry and exit, our method revealed that multiple branches enter and emerge from an area that extends up to one third of the organ's surface. This could be a prerequisite for the drastic and location-dependent remodeling of vascularization, which is necessary for lymph node expansion during inflammation. Contrary to corrosion cast studies we identified B-cell follicles exhibiting a two times denser capillary network than the deep cortical units of the T-cell zone. In addition to our observation of high endothelial venules spatially surrounding the follicles, this suggests a direct connection between morphology and B-cell homing. Our findings will deepen the understanding of functional lymph node composition and lymphocyte migration on a fundamental basis.

High-resolution and sensitivity bi-directional x-ray phase contrast imaging using 2D Talbot array illuminators

Two-dimensional (2D) Talbot array illuminators (TAIs) were designed, fabricated, and evaluated for high-resolution high-contrast x-ray phase imaging of soft tissue at 10-20 keV. The TAIs create intensity modulations with a high compression ratio on the micrometer scale at short propagation distances. Their performance was compared with various other wavefront markers in terms of period, visibility, flux efficiency, and flexibility to be adapted for limited beam coherence and detector resolution. Differential x-ray phase contrast and dark-field imaging were demonstrated with a one-dimensional, linear phase stepping approach yielding 2D phase sensitivity using unified modulated pattern analysis (UMPA) for phase retrieval. The method was employed for x-ray phase computed tomography reaching a resolution of 3 µm on an unstained murine artery. It opens new possibilities for three-dimensional, non-destructive, and quantitative imaging of soft matter such as virtual histology. The phase modulators can also be used for various other x-ray applications such as dynamic phase imaging, super-resolution structured illumination microscopy, or wavefront sensing.

Prognostic implications of cholesterol chrystals at ACS causing culprit lesions, insights from the translational OPTICO-ACS study program

Aims

Cholesterol chrystals (CC) represent a feature of advanced plaque remodeling. Optical coherence tomography (OCT) allows for detailed morphological assessment of the culprit lesion, including the presence of CCs, in vivo. Since CCs have been identified as prognostically relevant plaque feature in coronary artery disease (CAD), the present analysis aims to further characterize their impact on adverse cardiovascular outcome in a large cohort of patients, presenting with acute coronary syndrome (ACS).

Methods

Within the translational OPTICO-ACS study program, 371 consecutive ACS-patients were included into the final analysis. OCT-characteristics, including the presence of CCs, were assessed by a standardized CoreLab analysis following universal consensus standards for OCT-derived plaque features. All patients were followed up for 12 months after the index event and major adverse cardiac events (MACE) consisting of death, myocardial infarction, target vessel revascularization plus re-hospitalization due to unstable or progressive angina pectoris were documented.

Results

215 patients (58.1%) presented with cholesterol chrystals (CCs) at the culprit lesion. Plaque rupture (RFC-ACS) represented the primary ACS-causing pathophysiology (75.3%) in those patients. Further, the presence of CCs was associated with other high-risk features within the culprit lesion, i.e. the presence of thin cap fibroatheroma (77.7% vs. 63.2%; p<0.05), plaque calcification (80.5% vs. 67.1; p<0.01) and microchannels (80.1% vs. 70.1; p<0.05) as well as an increased area stenosis (0.77 vs. 0.73 mm2; p<0.01) and a greater maximum lipid arc (282.8 vs. 242.6°; p<0.01) as compared to culprit lesions free of CCs. Of note, there was a strong association among the occurrence of macrophages within the plaque and cholesterol crystals. Finally, and most importantly MACE during 12 months follow-up, consisting of cardiac death, myocardial infarction, target vessel revascularization and re-hospitalization due to progressive or unstable angina pectoris, occurred with nearly twice the frequency in CC-patients (20.3% vs. 10.6%; p<0.01) as compared to patients without CCs at the culprit site.

Conclusion

The present analysis introduces cholesterol chrystals as a novel prognostically relevant high-risk plaque feature allowing individual risk stratification for patients after ACS.

Funding Acknowledgement

Type of funding sources: None.

Efficacy of Retreatment After Failed Direct-acting Antiviral Therapy in Patients With HCV Genotype 1-3 Infections

Hepatitis C virus infection is causing chronic liver disease, cirrhosis, and hepatocellular carcinoma. By combining direct-acting antivirals (DAAs), high sustained virologic response rates (SVRs) can be achieved. Resistance-associated substitutions (RASs) are commonly observed after DAA failure, and especially nonstructural protein 5A (NS5A) RASs may impact retreatment options.^1-3 Data on retreatment of DAA failure patients using first-generation DAAs are limited.^4-7 Recently, a second-generation protease- and NS5A-inhibitor plus sofosbuvir (voxilaprevir/velpatasvir/sofosbuvir [VOX/VEL/SOF]) was approved for retreatment after DAA failure.⁸ However, this and other second-generation regimens are not available in many resource-limited countries or are not reimbursed by regular insurance, and recommendations regarding the selection of retreatment regimens using first-generation DAAs are very important. This study aimed to analyze patients who were re-treated with first-generation DAAs after failure of a DAA combination therapy.

A pilot study of the safety and efficacy of amisulpride and risperidone in elderly psychotic patients

Objective

The primary objective of this randomised, active–controlled, parallel group, double-blind study was to evaluate the tolerability of treatment with either amisulpride or risperidone in elderly patients with schizophrenia aged over 65 years; evaluation of efficacy was a secondary objective.

Methods

The study included patients of either sex aged 65 years or older fulfilling DSM IV-diagnostic criteria for psychotic disorders and who presented psychotic symptoms severe enough to require antipsychotic medication. Subjects were randomly allocated to a flexible dose of either amisulpride (100–400 mg/day) or risperidone (1–4 mg/day) for six weeks following a three- to six-day placebo wash-out period. Safety assessment involved adverse event reporting, physical examination, blood pressure, heart rate and ECG monitoring, and laboratory tests. Extrapyramidal symptoms were evaluated with the Simpson–Angus Scale, Barnes Akathisia Scale and the AIMS. Efficacy parameters were changes in score on the PANSS, BPRS, CDS and MMSE scores.

Results

Thirty-eight patients were randomised, 25 to amisulpride and 13 to risperidone. A total of 26 adverse events were experienced by 10 patients in the amisulpride group and five patients in the risperidone group. One patient in each group discontinued the study due to the emergence of a movement disorder. Changes in scores on the three measures of extrapyramidal symptoms were similar in the two groups. The PANSS total score decreased by 27.8% in the amisulpride group and by 29% in the risperidone group between inclusion and study end.

Conclusion

Amisulpride and risperidone are generally well tolerated in elderly patients with schizophrenia. Both drugs appeared to be efficacious in this study population, with no differences in efficacy being observed. However, the sample size was too low to reveal potential inter-group differences. Both these atypical antipsychotics thus appear to be suitable for the treatment of schizophrenia in the elderly.

What are depressive symptoms in acutely ill patients with schizophrenia spectrum disorder?

Background:

Aim was to examine depressive symptoms in acutely ill schizophrenia patients on a single symptom basis and to evaluate their relationship with positive, negative and general psychopathological symptoms.

Methods:

Two hundred and seventy-eight patients suffering from a schizophrenia spectrum disorder were analysed within a naturalistic study by the German Research Network on Schizophrenia. Using the Calgary Depression Scale for Schizophrenia (CDSS) depressive symptoms were examined and the Positive and Negative Syndrome Scale (PANSS) was applied to assess positive, negative and general symptoms. Correlation and factor analyses were calculated to detect the underlying structure and relationship of the patient’s symptoms.

Results:

The most prevalent depressive symptoms identified were depressed mood (80%), observed depression (62%) and hopelessness (54%). Thirty-nine percent of the patients suffered from depressive symptoms when applying the recommended cut-off of a CDSS total score of > 6 points at admission. Negligible correlations were found between depressive and positive symptoms as well as most PANSS negative and global symptoms despite items on depression, guilt and social withdrawal. The factor analysis revealed that the factor loading with the PANSS negative items accounted for most of the data variance followed by a factor with positive symptoms and three depression-associated factors.

Limitations:

The naturalistic study design does not allow a sufficient control of study results for the effect of different pharmacological treatments possibly influencing the appearance of depressive symptoms.

Conclusion:

Results suggest that depressive symptoms measured with the CDSS are a discrete symptom domain with only partial overlap with positive or negative symptoms.

The validity of self-rated psychotic symptoms in depressed inpatients

Background

Self-ratings of psychotic experiences might be biased by depressive symptoms.

Method

Data from a large naturalistic multicentre trial on depressed inpatients (n = 488) who were assessed on a biweekly basis until discharge were analyzed. Self-rated psychotic symptoms as assessed with the 90-Item Symptom Checklist (SCL-90) were correlated with the SCL-90 total score, the SCL-90 depression score, the Beck Depression Inventory (BDI), the Hamilton Depression Rating Scale 21 item (HAMD-21) total score, the Montgomery Åsberg Depression Rating Scale (MADRS) total score and the clinician-rated paranoid-hallucinatory score of the Association for Methodology and Documentation in Psychiatry (AMDP) scale.

Results

At discharge the SCL-90 psychosis score correlated highest with the SCL-90 depression score (0.78, P<0.001) and with the BDI total score (0.64, P<0.001). Moderate correlations were found for the MADRS (0.34, P<0.001), HAMD (0.37, P<0.001) and AMDP depression score (0.33, P<0.001). Only a weak correlation was found between the SCL-90 psychosis score and the AMDP paranoid-hallucinatory syndrome score (0.15, P<0.001). Linear regression showed that change in self-rated psychotic symptoms over the treatment course was best explained by a change in the SCL-90 depression score (P<0.001). The change in clinician-rated AMDP paranoid-hallucinatory score had lesser influence (P = 0.02).

Conclusions

In depressed patients self-rated psychotic symptoms correlate poorly with clinician-rated psychotic symptoms. Caution is warranted when interpreting results from epidemiological surveys using self-rated psychotic symptom questionnaires as indicators of psychotic symptoms. Depressive symptoms which are highly prevalent in the general population might influence such self-ratings.

Heart Rate Variability and Omega-3 Index in Euthymic Patients with Bipolar Disorders

Background:

Affective disorders are associated with an increased risk of cardiovascular disease, which, at least partly, appears to be independent of psychopharmacological treatments used to manage these disorders. Reduced heart rate variability (SDNN) and a low Omega-3 Index have been shown to be associated with increased risk for death after myocardial infarction. Therefore, we set out to investigate heart rate variability and the Omega-3 Index in euthymic patients with bipolar disorders.

Methods:

We assessed heart rate variability (SDNN) and the Omega-3 Index in 90 euthymic, mostly medicated patients with bipolar disorders (Bipolar-I, Bipolar-II) on stable psychotropic medication, free of significant medical comorbidity and in 62 healthy controls. Heart rate variability was measured from electrocardiography under a standardized 30 minutes resting state condition. Age, sex, BMI, smoking, alcohol consumption and caffeine consumption as potential confounders were also assessed.

Results:

Heart rate variability (SDNN) was significantly lower in patients with bipolar disorders compared to healthy controls (35.4 msec versus 60.7 msec; P < 0.0001), whereas the Omega-3 Index did not differ significantly between the groups (5.2% versus 5.3%). In a linear regression model, only group membership (patients with bipolar disorders versus healthy controls) and age significantly predicted heart rate variability (SDNN).

Conclusion:

Heart rate variability (SDNN) may provide a useful tool to study the impact of interventions aimed at reducing the increased risk of cardiovascular disease in euthymic patients with bipolar disorders. The difference in SDNN between cases and controls cannot be explained by a difference in the Omega-3 Index.

P6394Neutrophil activation patterns in acute coronary syndrome with intact fibrous cap - results from the OPTICO-ACS study

Background

In up to one third of all cases, acute coronary syndrome occurs without signs of plaque rupture. Instead endothelial cell erosion is considered to be the hallmark of acute coronary syndrome with intact fibrous cap (IFC-ACS), with matrix metalloproteinase 9 (MMP9) directly linked to this pathology. The main source of MMP9 immediately after ACS are the neutrophil granulocytes. Therefore, their molecular activation patterns and subsequent MMP9 production are the objectives of the ongoing, translational OPTICO-ACS-Study, aiming to compare the mechanisms and prognosis of IFC-ACS and ACS with ruptured fibrous cap (RFC-ACS).

Methods

Local and systemic blood samples were simultaneously obtained from the site of the ACS-causing culprit lesion (LOC) using an aspiration catheter and from the systemic circulation (SYS). Using optical coherence tomography (OCT) the ACS-causing culprit lesion was characterized and two patient groups, patients with ACS caused by intact (IFC-ACS) and by ruptured fibrous cap (RFC-ACS) were compared. Each group consists of twenty patients (n=20) matched by age, gender and diabetes. Neutrophil counts and expression of activation markers were immediately quantified by whole-blood flow cytometry. Release of active MMP9 into the plasma was assessed by fluorescence-based zymography. Activation profiles of freshly isolated neutrophils, including MMP9 activity and effect on endothelial cell death, in response to toll-like receptor 2 (TLR2) stimulation was studied.

Results

Local neutrophils of patients with IFC-ACS show significantly higher expression of TLR2 in comparison to RFC-ACS neutrophils (LOC: 1866±382.1 vs. 1498±426.9; IFC-ACS vs. RFC-ACS, p=0.03). MMP9 activity is significant higher (p=0.01) in plasma obtained from the culprit site of IFC-ACS (74.1 U/ml±4.1) compared to those of RFC-ACS patients (70.0 U/ml±5.1) indicating secretion and activation of the enzyme during IFC-ACS. Importantly, in patients with IFC-ACS, TLR2-stimulation using Pam3CSK4 triggers higher activity rates of MMP9 only in neutrophils isolated directly from the culprit site (LOC), but not systemically (+27%±17.2% IFC-LOC vs. IFC-SYS; p=0.003). This effect was not observed in RFC-derived neutrophils. Inhibiting TLR2 by a monoclonal antibody, strongly reduced secretion of activated MMP9 only in the local neutrophils from IFC-ACS-patients (−54.6%±6.5% in IFC-LOC-anti-TLR2 vs. IFC-LOC-vehicle; p=0.008), but not from systemic IFC-neutrophils, nor from RFC-neutrophils. Furthermore, LOC IFC-ACS neutrophils aggravate endothelial cell death upon TLR2-activation in comparison to LOC RFC-ACS neutrophils (58.4±4.96% vs. 20±1.89%, IFC-ACS vs. RFC-ACS; p=0.0023).

Conclusion

We newly describe differential kinetics of MMP9 release by neutrophils in ACS patients with IFC versus RFC. Our data support a role of a TLR-2 activated and neutrophil-MMP9-mediated mechanism leading to endothelial cell erosion in patients with IFC-ACS.

Acknowledgement/Funding

DZHK (German Centre for Cardiovascular Research); BIH (Berlin Institute of Health)

Medikamentöse Akutbehandlung schizophrener Ersterkrankungen

Atypische Neuroleptika werden heute für die Behandlung von Patienten mit schizophrenen Erkrankungen als Therapie der ersten Wahl empfohlen, da sie gegenüber den typischen Neuroleptika deutliche Vorteile hinsichtlich des Wirkungsspektrums und des Nebenwirkungsprofils aufweisen. Dies trifft insbesondere für ersterkrankte Patienten zu, da für diese Patientengruppe im Vergleich zu Mehrfacherkrankten ein höheres Risiko für extrapyramidal-motorische Nebenwirkungen beschrieben wurde. Ob die Vorteile der atypischen Neuroleptika aber auch nachweisbar sind, wenn typische Neuroleptika in niedrigen Dosierungen eingesetzt werden, ist bisher empirisch unzureichend geprüft. Vor diesem Hintergrund wurden im Rahmen einer multizentrischen, doppelblinden, randomisierten klinischen Studie des Kompetenznetz Schizophrenie die Effekte von Risperidon und Haloperidol im Niedrigdosisbereich (Tagesdosen von 2 mg bis maximal 8 mg für beide Medikamente) in der Akutbehandlung ersterkrankter Patienten verglichen.

Gas hydrate dissociation off Svalbard induced by isostatic rebound rather than global warming

Methane seepage from the upper continental slopes of Western Svalbard has previously been attributed to gas hydrate dissociation induced by anthropogenic warming of ambient bottom waters. Here we show that sediment cores drilled off Prins Karls Foreland contain freshwater from dissociating hydrates. However, our modeling indicates that the observed pore water freshening began around 8 ka BP when the rate of isostatic uplift outpaced eustatic sea-level rise. The resultant local shallowing and lowering of hydrostatic pressure forced gas hydrate dissociation and dissolved chloride depletions consistent with our geochemical analysis. Hence, we propose that hydrate dissociation was triggered by postglacial isostatic rebound rather than anthropogenic warming. Furthermore, we show that methane fluxes from dissociating hydrates were considerably smaller than present methane seepage rates implying that gas hydrates were not a major source of methane to the oceans, but rather acted as a dynamic seal, regulating methane release from deep geological reservoirs.

Methane seepage from continental slopes has been attributed to gas hydrate dissociation induced by anthropogenic bottom water warming. Here, the authors show that hydrates dissociated before the Anthropocene when the isostatic rebound induced by deglaciation of the Arctic ice sheet outpaced eustatic sea-level rise.

InGaN/GaN nanowires as a new platform for photoelectrochemical sensors - detection of NADH

InGaN/GaN nanowire heterostructures are presented as nanophotonic probes for the light-triggered photoelectrochemical detection of NADH. We demonstrate that photogenerated electron-hole pairs give rise to a stable anodic photocurrent whose potential- and pH-dependences exhibit broad applicability. In addition, the simultaneous measurement of the photoluminescence provides an additional tool for the analysis and evaluation of light-triggered reaction processes at the nanostructured interface. InGaN/GaN nanowire ensembles can be excited over a wide wavelength range, which avoids interferences of the photoelectrochemical response by absorption properties of the compounds to be analyzed by adjusting the excitation wavelength. The photocurrent of the nanostructures shows an NADH-dependent magnitude. The anodic current increases with rising analyte concentration in a range from 5µM to 10mM, at a comparatively low potential of 0mV vs. Ag/AgCl. Here, the InGaN/GaN nanowires reach high sensitivities of up to 91µAmM^-1cm^-2 (in the linear range) and provide a good reusability for repetitive NADH detection. These results demonstrate the potential of InGaN/GaN nanowire heterostructures for the defined conversion of this analyte paving the way for the realization of light-switchable sensors for the analyte or biosensors by combination with NADH producing enzymes.

Connecting quantum dots with enzymes: mediator-based approaches for the light-directed read-out of glucose and fructose oxidation

The combination of the biocatalytic features of enzymes with the unique physical properties of nanoparticles in a biohybrid system provides a promising approach for the development of advanced bioelectrocatalytic devices. This study describes the construction of photoelectrochemical signal chains based on CdSe/ZnS quantum dot (QD) modified gold electrodes as light switchable elements, and low molecular weight redox molecules for the combination with different biocatalysts. Photoelectrochemical and photoluminescence experiments verify that electron transfer can be achieved between the redox molecules hexacyanoferrate and ferrocene, and the QDs under illumination. Since for both redox mediators a concentration dependent photocurrent change has been found, light switchable enzymatic signal chains are built up with fructose dehydrogenase (FDH) and pyrroloquinoline quinone-dependent glucose dehydrogenase ((PQQ)GDH) for the detection of sugars. After immobilization of the enzymes at the QD electrode the biocatalytic oxidation of the substrates can be followed by conversion of the redox mediator in solution and subsequent detection at the QD electrode. Furthermore, (PQQ)GDH has been assembled together with ferrocenecarboxylic acid on top of the QD electrode for the construction of a funtional biohybrid architecture, showing that electron transfer can be realized from the enzyme over the redox mediator to the QDs and subsequently to the electrode in a completely immobilized fashion. The results obtained here do not only provide the basis for light-switchable biosensing and bioelectrocatalytic applications, but may also open the way for self-driven point-of-care systems by combination with solar cell approaches (power generation at the QD electrode by enzymatic substrate consumption).

Representation of the characteristic function of a stochastic integral

Let X(t) be a continuous, homogeneous stochastic process with independent increments characterized by a, σ, M, N in the Lévy representation formula. In this note we obtain the Lévy canonical representation of the characteristic function of a stochastic integral (in the sense of convergence in probability) of the form (where υ(t) is a non-decreasing, non-negative and left-continuous function) in terms of υ(t), a, σ, M, N.

Characterization of stable processes by identically distributed stochastic integrals

Let X(t) be a homogeneous and continuous stochastic process with independent increments. The subject of this paper is to characterize the stable process by two identically distributed stochastic integrals formed by means of X(t) (in the sense of convergence in probability). The proof of the main results is based on a modern extension of the Phragmén-Lindelöf theory.