Extreme wave excitation from localized phase-shift perturbations

The modulation instability is a focusing mechanism responsible for the formation of strong wave localizations not only on the water surface, but also in a variety of nonlinear dispersive media. Such dynamics is initiated from the injection of sidebands, which translate into an amplitude modulation of the wave field. The nonlinear stage of unstable wave evolution can be described by exact solutions of the nonlinear Schrödinger equation (NLSE). In that case, the amplitude modulation of such coherent extreme wave structures is connected to a particular phase-shift seed in the carrier wave. In this Letter, we show that phase-shift localization applied to the background, excluding any amplitude modulation excitation, can indeed trigger extreme events. Such rogue waves can be for instance generated by considering the parametrization of fundamental breathers, and thus by seeding only the local phase-shift information to the regular carrier wave. Our wave tank experiments show an excellent agreement with the expected NLSE hydrodynamics and confirm that even though delayed in their evolution, breather-type extreme waves can be generated from a purely regular wave train. Such a focusing mechanism awaits experimental confirmation in other nonlinear media, such optics, plasma, and Bose-Einstein condensates.

Parameter Identification for Ultrasound Shear Wave Elastography Simulation

Elasticity of soft tissue is a valuable information to physicians in treatment and diagnosis of diseases. The elastic properties of tissue can be estimated with ultrasound (US) shear wave imaging (SWEI). In US-SWEI, a force push is applied inside the tissue and the resulting shear wave is detected by high-frequency imaging. The properties of the wave such as the shear wave velocity can be mapped to tissue elasticity. Commonly, wave features are extracted by tracking the peak of the shear wave, estimating the phase velocity or with machine learning methods. To tune and test these methods, often simulation data is employed since material properties and excitation can be accurately controlled. Subsequent validation on real US-SWEI data is in many cases performed on tissue phantoms such as gelatine. Clearly, validation performance of these procedures is dependent on the accuracy of the simulated tissue phantom and a thorough comparison of simulation and experimental data is needed. In this work, we estimate wave parameters from 400 US-SWEI data sets acquired in various homogeneous gelatine phantoms. We tune a linear material model to these parameters. We report an absolute percentage error for the shear wave velocity between simulation and phantom experiment of <2.5%. We validate our material model on unknown gelatine concentrations and estimate the shear wave velocity with an error <3.4% for in-range concentrations indicating that our material model is in good agreement with US-SWEI measurements.

660 Chronotype Associations with Insomnia, Depressive Symptoms, and Changes in Sleep and Health Behaviors during the COVID-19 Pandemic

Introduction

Evening chronotype (i.e., night owl preference) is associated with worse insomnia and depressive symptoms, and poorer health behaviors. The aim of this study was to examine the association between chronotype and these symptoms and health behaviors during COVID-19 pandemic quarantine.

Methods

An online survey, distributed internationally via social media from 5/21/2020–7/1/2020, asked adults to report sociodemographic/economic information, changes in sleep (midpoint, total sleep time, sleep efficiency, time-in-bed), and health behaviors (i.e., physical activity, sedentary screen time, and outdoor light exposure patterns) from prior to during the pandemic, chronotype preference (definitely morning [DM], rather more morning [RM], rather more evening [RE], or definitely evening [DE]), and complete the Insomnia Severity Index (ISI) and the 10-item Center for Epidemiologic Studies Depression scale (CES-D-10). Multinomial logistic regression and ANCOVA models, adjusting for age and sex, examined associations of chronotype with COVID-19 pandemic related impacts on sleep, depressive symptoms, and health behaviors.

Results

A subsample of 579 participants (M age: 39y, range: 18–80; 73.6% female), currently under quarantine and neither pregnant nor performing shift work, represented each chronotype evenly (~25%). Participants delayed their sleep midpoint by 72.0min (SD=111.5) during the pandemic. DE chronotypes had a greater delay than morning types (M±SD DE: 91.0±9.0 vs. RM: 55.9±9.2 & DM: 66.1±9.3; p=0.046) with no significant change in other sleep patterns relative to other chronotypes. However, DE and RE chronotypes had greater odds of reporting that their new sleep/wake schedule was still not consistent with their “body clock” preference relative to morning types (Χ2[15]=54.8, p<0.001), reported greater ISI (F[3,503]=5.3, p=.001) and CES-D-10 scores (F[3,492]=7.9, p<.001), and had greater odds for increased or consistently moderate-to-high sedentary screen time (Χ2[12]=22.7, p=0.03) and decreased physical activity (Χ2[12]=22.5, p=0.03) than DM chronotype. There was no significant difference in change in outdoor light exposure by chronotype (Χ2[12]=12.1, p=0.43).

Conclusion

In an international online sample of adults under COVID-19 pandemic quarantine, evening chronotypes, despite taking the opportunity to delay sleep to match biological clock preference, reported their sleep/wake schedules were still inconsistent with personal preference, and reported greater insomnia and depressive symptoms, and odds of engaging in poorer health behaviors than morning chronotypes.

Support (if any):

Glucose metabolism in patients with psoriasis

BACKGROUND

Epidemiological studies strongly suggest that psoriasis predisposes to type 2 diabetes. Several theories have been proposed to explain how these disease entities might be pathophysiologically connected.

OBJECTIVES

Our primary objective was to elucidate whether clinical data support the notion of common pathophysiological denominators in patients with psoriasis and type 2 diabetes, and thus to delineate the association between the two conditions that has arisen on the basis of epidemiological studies.

METHODS

We reviewed clinical studies investigating parameters of glucose metabolism in patients with psoriasis. The PubMed and Embase databases were searched for studies investigating glucose metabolism in adult patients with psoriasis as a primary or secondary end point. Studies had to include a relevant control group.

RESULTS

Twenty-six clinical studies reporting on insulin resistance, glucose tolerance or insulin secretion were eligible for review. The results were widely conflicting, with less than half of the studies showing results suggestive of defective glucose metabolism in patients with psoriasis. In general, the studies suffered from a lack of information regarding possible confounders and patient characteristics. Furthermore, the research methods varied, and in all but one study they might not have been appropriate to detect early and subtle defects in glucose metabolism.

CONCLUSIONS

The available literature does not unequivocally support common pathophysiological denominators in psoriasis and type 2 diabetes. Well-designed clinical studies are needed to expose potential diabetogenic defects in the glucose metabolism in patients with psoriasis.

Brain boosters: Evaluating a pilot program for memory complaints in veterans

This study investigated the feasibility and preliminary effectiveness of a pilot program designed to address subjective memory complaints among Veterans. The program, Brain Boosters, consisted of 10 once-weekly group sessions, during which psychoeducation and cognitive enhancement strategies were used to target memory concerns and related processes, specifically attentional difficulties. Given that memory complaints often are associated with psychiatric comorbidities, sessions also incorporated strategies for reducing symptoms of depression, posttraumatic stress, and insomnia. Controlling for age, we examined pre- to posttreatment change in symptom ratings for 96 Veterans (aged 22 to 87 years) who participated in the Brain Boosters program. The effect of Brain Boosters on memory complaints interacted with age: younger (but not older) Veterans reported reductions in memory impairment from pre- to posttreatment. Additionally, irrespective of age, from pre- to posttreatment Veterans reported fewer attentional difficulties and fewer depression symptoms. Ratings of posttraumatic stress and insomnia symptoms did not change, although insomnia was negatively associated with age. Linear regression controlling for age revealed that reductions in attention problems predicted reductions in perceived memory impairment. Findings from this exploratory, uncontrolled pilot study suggest that a psychoeducational cognitive enhancement group is feasible to conduct in a heterogeneous Veteran population, and may be associated with improvements in perceived memory functioning for younger Veterans, and in attention and depression symptoms for Veterans across age groups. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Detection of unstable periodic orbits in mineralising geological systems

Worldwide, mineral exploration is suffering from rising capital costs, due to the depletion of readily recoverable reserves and the need to discover and assess more inaccessible or geologically complex deposits. For gold exploration, this problem is particularly acute. We propose an innovative approach to mineral exploration and orebody characterisation, based on the analysis of geological core data as a spatial dynamical system, using the mathematical tools of dynamical system analysis. This approach is highly relevant for orogenic gold deposits, which-in contrast to systems formed at chemical equilibrium-exhibit many features of nonlinear dynamical systems, including episodic fluctuations on various length and time scales. Feedback relationships between thermo-chemical and deformation processes produce recurrent fluid temperatures and pressures and the deposition of vein-filling minerals such as pyrite and gold. We therefore relax the typical assumption of chemical equilibrium and analyse the underlying processes as aseismic, non-adiabatic, and inherent to a hydrothermal, nonlinear dynamical open-flow chemical reactor. These processes are approximated using the Gray-Scott model of reaction-diffusion as a complex toy system, which captures some of the features of the underlying mineralisation processes, including the spatiotemporal Turing patterns of unsteady chemical reactions. By use of this analysis, we demonstrate the capability of recurrence plots, recurrence power spectra, and recurrence time probabilities to detect underlying unstable periodic orbits as one sign of deterministic dynamics and their robustness for the analysis of data contaminated by noise. Recurrence plot based quantification is then applied to three mineral concentrations in the core data from the Sunrise Dam gold deposit in the Yilgarn region of Western Australia. Using a moving window, we reveal the episodic recurring low-dimensional dynamic structures and the period doubling route to instability with depth, embedded in and originating from higher-dimensional processes of the complex mineralisation system.

Phase Domain Walls in Weakly Nonlinear Deep Water Surface Gravity Waves

We report a theoretical derivation, an experimental observation and a numerical validation of nonlinear phase domain walls in weakly nonlinear deep water surface gravity waves. The domain walls presented are connecting homogeneous zones of weakly nonlinear plane Stokes waves of identical amplitude and wave vector but differences in phase. By exploiting symmetry transformations within the framework of the nonlinear Schrödinger equation we demonstrate the existence of exact analytical solutions representing such domain walls in the weakly nonlinear limit. The walls are in general oblique to the direction of the wave vector and stationary in moving reference frames. Experimental and numerical studies confirm and visualize the findings. Our present results demonstrate that nonlinear domain walls do exist in the weakly nonlinear regime of general systems exhibiting dispersive waves.

Lipidomics informatics for life-science

Lipidomics encompasses analytical approaches that aim to identify and quantify the complete set of lipids, defined as lipidome in a given cell, tissue or organism as well as their interactions with other molecules. The majority of lipidomics workflows is based on mass spectrometry and has been proven as a powerful tool in system biology in concert with other Omics disciplines. Unfortunately, bioinformatics infrastructures for this relatively young discipline are limited only to some specialists. Search engines, quantification algorithms, visualization tools and databases developed by the 'Lipidomics Informatics for Life-Science' (LIFS) partners will be restructured and standardized to provide broad access to these specialized bioinformatics pipelines. There are many medical challenges related to lipid metabolic alterations that will be fostered by capacity building suggested by LIFS. LIFS as member of the 'German Network for Bioinformatics' (de.NBI) node for 'Bioinformatics for Proteomics' (BioInfra.Prot) and will provide access to the described software as well as to tutorials and consulting services via a unified web-portal.

In situ starch and crude protein degradation in the rumen and in vitro gas production kinetics of wheat genotypes

The objective of this study was to determine the variation of in situ ruminal degradation characteristics of dry matter (DM), crude protein (CP) and starch (ST), and to determine the effective degradation (ED) of wheat genotypes. Further, multivariate associations of these in situ values with their corresponding in vitro gas production (GP) kinetics and laboratory measurements were evaluated using correlation and multiple linear regression analyses. Grains of 20 genotypes of wheat were characterized by proximate constituents, amino acid (AA) composition and physical characteristics. Ruminal degradation kinetics were determined by in situ degradation of DM, CP and ST, and subsequent evaluation of in vitro GP relative to time courses. In situ and GP measurements were fitted to an exponential equation, and ED was calculated using passage rates in the rumen of 5%/h (ED5) and 8%/h (ED8). To predict ED8 of CP (EDCP8) and ST (EDST8), correlations were evaluated and stepwise multiple linear regression analyses were applied. Estimated degradation parameters varied considerably between wheat genotypes irrespective of the nutrient tested. Variance in a, b and c was not reflected in the variation of the ED, due to high degradation rates (c). The assumed passage rate also impacted estimation of the ED minimally. Estimated GP parameters varied only slightly among wheat genotypes. Nevertheless, regression models explained up to 80 and 99% of the variance in EDCP8 and EDST8, respectively, and associations between EDST8 and EDCP8 and chemical and physical characteristics of grains were detected. As ST is the primary nutrient in wheat grains and can comprise substantial portions of dairy rations, the total amount of ST as well as its ED in the rumen should be taken into account when wheat is incorporated into dairy rations. Conversely, variance in wheat grain CP degradation was very low and can largely be neglected in practical ration formulation for ruminants.

Stability and activity of MCSP-specific chimeric antigen receptors (CARs) depend on the scFv antigen-binding domain and the protein backbone

Chimeric antigen receptor (CAR)-modified T cells emerged as effective tools in the immunotherapy of cancer but can produce severe on-target off-tissue toxicities. This risk can conceivably be overcome, at least partially, by transient transfection. The design of CARs, however, has so far not been optimized for use in non-permanent T cell modification. Here we compared the performance of T cells modified with three different first- and second-generation CARs, each specific for MCSP (HMW-MAA) which is commonly expressed by melanoma cells. Upon RNA transfer, the expression of all receptors was limited in time. The second-generation CARs, which combined CD28-CD3ζ signaling, were expressed at higher levels and more prolonged than first-generation CARs with CD3ζ only. The CD28 domain increased the cytokine production, but had only an indirect effect on the lytic capacity, by prolonging the CAR expression. Especially for the second-generation CARs, the scFv clearly impacted the level and duration of CAR expression and the T cell performance. Thus, we identified a CAR high in both expression and anti-tumor cell reactivity. T cells transfected with this CAR increased the mean survival time of mice after challenge with melanoma cells. To facilitate clinical application, this CAR was used to redirect T cells from late-stage melanoma patients by RNA transfection. These T cells mediated effective antigen-specific tumor cell lysis and release of pro-inflammatory cytokines, even after cryoconservation of the transfected T cells. Taken together, the analysis identified a CAR with superior anti-melanoma performance after RNA transfer which is a promising candidate for clinical exploration.

Gray solitons on the surface of water

The dynamics of surface gravity water waves can be described by the self-defocusing nonlinear Schrödinger equation. Recent observations of black solitons on the surface of water confirmed its validity for finite, below critical depth. The black soliton is a limiting case of a family of gray soliton solutions with finite amplitude depressions. Here, we report observations of gray solitons in water waves, thus, complementing our previous observations of black solitons.

Hydrodynamic supercontinuum

We report the experimental observation of multi-bound-soliton solutions of the nonlinear Schrödinger equation (NLS) in the context of hydrodynamic surface gravity waves. Higher-order N-soliton solutions with N=2, 3 are studied in detail and shown to be associated with self-focusing in the wave group dynamics and the generation of a steep localized carrier wave underneath the group envelope. We also show that for larger input soliton numbers, the wave group experiences irreversible spectral broadening, which we refer to as a hydrodynamic supercontinuum by analogy with optics. This process is shown to be associated with the fission of the initial multisoliton into individual fundamental solitons due to higher-order nonlinear perturbations to the NLS. Numerical simulations using an extended NLS model described by the modified nonlinear Schrödinger equation, show excellent agreement with experiment and highlight the universal role that higher-order nonlinear perturbations to the NLS play in supercontinuum generation.

Super-rogue waves in simulations based on weakly nonlinear and fully nonlinear hydrodynamic equations

The rogue wave solutions (rational multibreathers) of the nonlinear Schrödinger equation (NLS) are tested in numerical simulations of weakly nonlinear and fully nonlinear hydrodynamic equations. Only the lowest order solutions from 1 to 5 are considered. A higher accuracy of wave propagation in space is reached using the modified NLS equation, also known as the Dysthe equation. This numerical modeling allowed us to directly compare simulations with recent results of laboratory measurements in Chabchoub et al. [Phys. Rev. E 86, 056601 (2012)]. In order to achieve even higher physical accuracy, we employed fully nonlinear simulations of potential Euler equations. These simulations provided us with basic characteristics of long time evolution of rational solutions of the NLS equation in the case of near-breaking conditions. The analytic NLS solutions are found to describe the actual wave dynamics of steep waves reasonably well.

Experimental observation of dark solitons on the surface of water

We present the first ever observation of dark solitons on the surface of water. It takes the form of an amplitude drop of the carrier wave which does not change shape in propagation. The shape and width of the soliton depend on the water depth, carrier frequency, and the amplitude of the background wave. The experimental data taken in a water tank show an excellent agreement with the theory. These results may improve our understanding of the nonlinear dynamics of water waves at finite depths.

Observation of a hierarchy of up to fifth-order rogue waves in a water tank

We present experimental observations of the hierarchy of rational breather solutions of the nonlinear Schrödinger equation (NLS) generated in a water wave tank. First, five breathers of the infinite hierarchy have been successfully generated, thus confirming the theoretical predictions of their existence. Breathers of orders higher than five appeared to be unstable relative to the wave-breaking effect of water waves. Due to the strong influence of the wave breaking and relatively small carrier steepness values of the experiment these results for the higher-order solutions do not directly explain the formation of giant oceanic rogue waves. However, our results are important in understanding the dynamics of rogue water waves and may initiate similar experiments in other nonlinear dispersive media such as fiber optics and plasma physics, where the wave propagation is governed by the NLS.

Biodiversity information platforms: From standards to interoperability

One of the most serious bottlenecks in the scientific workflows of biodiversity sciences is the need to integrate data from different sources, software applications, and services for analysis, visualisation and publication. For more than a quarter of a century the TDWG Biodiversity Information Standards organisation has a central role in defining and promoting data standards and protocols supporting interoperability between disparate and locally distributed systems.Although often not sufficiently recognized, TDWG standards are the foundation of many popular Biodiversity Informatics applications and infrastructures ranging from small desktop software solutions to large scale international data networks. However, individual scientists and groups of collaborating scientist have difficulties in fully exploiting the potential of standards that are often notoriously complex, lack non-technical documentations, and use different representations and underlying technologies. In the last few years, a series of initiatives such as Scratchpads, the EDIT Platform for Cybertaxonomy, and biowikifarm have started to implement and set up virtual work platforms for biodiversity sciences which shield their users from the complexity of the underlying standards. Apart from being practical work-horses for numerous working processes related to biodiversity sciences, they can be seen as information brokers mediating information between multiple data standards and protocols.The ViBRANT project will further strengthen the flexibility and power of virtual biodiversity working platforms by building software interfaces between them, thus facilitating essential information flows needed for comprehensive data exchange, data indexing, web-publication, and versioning. This work will make an important contribution to the shaping of an international, interoperable, and user-oriented biodiversity information infrastructure.

Propofol, remifentanil and mivacurium: fast track surgery with poor intubating conditions

BACKGROUND

Mivacurium is widespread used because it is the non-depolarizing muscle relaxant with the shortest duration time. Therefore, it seems to be ideal for fast track or ambulatory surgery. However, especially in combination with propofol and remifentanil onset time remains unclear and incidence of poor intubating conditions seems to be higher than in other regimes of anesthesia.

METHODS

We included 35 ear, nose and throat (ENT) patients in this study. Muscle relaxation was measured by acceleromyograhpy at the adductor pollicis muscle (a.p.m.) and intubating conditions were evaluated. Anesthesia was induced with 2.5 mg kg-1 propofol and 1 µg kg-1 remifentanil and intubation was performed three minutes after the administration of 0.2 mg kg-1 mivacurium. Open vocal cords conjoined with full relaxation of the a.p.m., easy mouth opening and prevention of coughing and bucking represented the primary endpoint in this study.

RESULTS

Only 20% of patients (N.=7) had optimal intubating conditions and achieved the primary endpoint. In 21 patients (60%) a complete block of the a.p.m. could not be achieved and in six patients (17%) the vocal cords were closed. In seven patients (20%) we observed difficult mouth opening and in 11 patients (31%) coughing and bucking. In addition, we found a prolonged onset time of 228±95 seconds (mean±SD).

CONCLUSION

In combination with propofol and remifentanil the muscle relaxant agent mivacurium led to uncertain muscle relaxation and to poor intubating conditions. Therefore the study was aborted after 35 patients. Probably mivacurium is not a useful muscle relaxant agent if fast and deep muscle relaxation is needed. The advantage of a short duration time is foiled by intubation complications due to insufficient muscle relaxation.

Macrophage colony-stimulating factor (M-CSF) in plasma and CSF of patients with mild cognitive impairment and Alzheimer's disease

Macrophage colony-stimulating factor (M-CSF) is a hematopoietic growth factor that activates microglial cells, involved in phagocytosis of amyloid-beta (Abeta) in the brain. In the present study, we found in 50 patients with Alzheimer's disease (AD) significantly increased M-CSF plasma levels compared to 22 patients with mild cognitive impairment (MCI) and 35 age-matched healthy controls. In contrast, MCI patients showed significantly decreased M-CSF levels in cerebrospinal fluid (CSF) compared to AD patients and 20 patients with other non-inflammatory neurological disease (NIND). Analyzing the impact of Beta-amyloid 1-42 (Abeta 1-42), tau protein and M-CSF for differentiation between the groups we found that M-CSF, but not Abeta 1-42 and tau-protein is a significant parameter for distinction between MCI and NIND patients with 68.8% sensitivity and 75.0% specificity. M-CSF CSF levels < or = 357.8 pg/ml yielded 73.7% sensitivity and 75.0% specificity for diagnosing MCI patients in comparison with control subjects. In conclusion, our data indicate that M-CSF in CSF could be a putative biomarker for MCI.

Area at risk and viability after myocardial ischemia and reperfusion can be determined by contrast-enhanced cardiac magnetic resonance imaging

BACKGROUND/AIMS

Clinical differentiation between infarcted and viable myocardium in the ischemic area at risk is controversial. We investigated the potential of contrast-enhanced cardiac magnetic resonance imaging (ceCMRI) in determining the area at risk 24 h after ischemia.

METHODS

Myocardial ischemia was induced by percutaneous coronary intervention of the left anterior descending coronary artery in pigs. Coronary occlusion time was 30 min in group A, which caused little myocardial infarction and 45 min in group B, which led to irreversible damage. 24 h after reperfusion ceCMRI was performed at 2 and 15 min after administration of gadolinium-diethylenetriamine pentaacetic acid. The area at risk was determined by intravenous injection of Evans blue and myocardial viability by triphenyltetrazolium-chloride staining.

RESULTS

The signal-intense areas at 2 and 15 min after contrast administration matched the area at risk in groups A and B. Nonviable myocardium in group A was overestimated (14-15%) while good agreement was present in group B.

CONCLUSION

The area at risk of reperfused ischemic myocardium can be determined by ceCMRI 24 h after coronary recanalization. This type of information might have relevant clinical implications in the treatment and stratification of patients with acute coronary syndrome in particular after surgical interventions.

["Meet the AIX-PERTs." Emergency medical care at the beginning of the medical reform curriculum in Aachen]

BACKGROUND

Extensive knowledge and skills in the basics of emergency medical care are of paramount importance for every physician and should therefore be an integral part of medical education.

METHODS

Regulations for medical licensure in Germany were revised by the administrative authorities in 2002 and as a consequence the Medical Faculty of the University of Aachen (Germany) decided to start the Medical Reform Curriculum Aachen. A multidisciplinary, problem-oriented and organ-related approach to medical education replaces the classical discrimination between basic and clinical sciences.

RESULTS

With AIX-PERT (AIX-la-Chapelle Program for Emergency medical care and Resuscitation Training), a program consisting of problem-based learning sessions was developed for introduction to the first year students. Defined teaching objectives in emergency medicine are now incorporated in undergraduate medical education.

CONCLUSION

The extremely positive evaluation of the new approach encouraged us to promote AIX-PERT further. In the future the effects of success of this approach will be assessed by longitudinal studies of skills and knowledge during the continuing curriculum.

Fulminant liver failure induced by hepatosplenic alphabeta T-cell lymphoma

Since survival rates of fulminant liver failure are low, early consideration of liver transplantation in patients developing hepatic encephalopathy due to progressive liver failure is mandatory. Rapid diagnostic work-up is necessary to identify the underlying disease and to rule out contraindications to liver transplantation. We report the case of a 35-year-old patient presenting with fulminant hepatitis and a four-week history of biopsy-proven autoimmune hepatitis. Despite high-dose steroid-treatment liver function progressively worsened and hepatic encephalopathy rapidly developed. Histopathologic evaluation of a liver biopsy specimen revealed necrotizing hepatitis and rare atypical lymphocytes. Surgical biopsy specimens confirmed the suspicion of an aggressive hepatosplenic alphabeta T-cell lymphoma which represents a contraindication to liver transplantation.

Efficient radical addition of tertiary amines to electron-deficient alkenes using semiconductors as photochemical sensitisers

Tertiary amines can be added to electron-deficient alkenes with yields up to 98% in a radical chain reaction initiated by a photochemical electron transfer using inorganic semiconductors like TiO2 as sensitiser.

Selective and sensitive detection of pectin lyase activity using a colorimetric test: application to the screening of microorganisms possessing pectin lyase activity

Several methods have been described for the detection and quantification of polygalacturonase (PG) and pectin lyase (PL) activities. The most frequently used tests are the Nelson method using copper(II) and an arsenomolybdate reagent to detect PG activity, and the colorimetric method using thiobarbituric acid (TBA) to detect PL activity. We observed that none of these methods are suitable to differentiate between these two enzymatic activities. Therefore, we optimized the test conditions of the TBA method. As a result, the detection of the enzymatic beta-elimination (PL activity) became sensitive and selective. A basic pretreatment at 80 degrees C for 5 min of the solution which contains the pectin fragments of the PL activity furnished aldehydes which were condensed with TBA or its derivatives. After acidification of the medium, a pink fluorescent dye was detected spectrophotochemically (lambda = 550 nm). The interference of galacturonic acid or oligomers resulting from PG activity was completely eliminated. The most sensitive reagent was N-(pyridin-2-yl)-thiobarbituric acid. The application of this method with the new reagent was extended to the screening of microorganisms possessing the PL activity. The obtained results confirm that Aspergillus niger strain and a Saccharomyces cerevisiae SCPP strain possess this activity.

Diastereoselective tandem addition-cyclization reactions of unsaturated tertiary amines initiated by photochemical electron transfer (PET)

Polycyclic molecules and tetrahydroquinoleines were obtained in a tandem reaction involving the diastereoselective addition of alpha-aminoalkyl radicals to (5R)-5-menthyloxy-2[5H]-furanone 1. The facial diastereoselectivity on 1 is >/=90%. The alpha-aminoalkyl radicals were produced from tertiary amines by photochemical-induced electron transfer. When N,N-dialkylanilines 19 were used as starting tertiary amines, a rearomatization step was involved and important side reactions of 1 were observed. A mechanistic study involving isotopic labeling of the starting amine indicated that the byproducts resulted from reduction of 1 during the rearomatization process. An efficient optimization of the reaction was obtained by simply adding acetone or cyclopentanone as mild oxidants to the reaction mixture. The side products resulting from reduction of the furanone 1 were completely suppressed under these conditions, and the yields of the tetrahydroquinolines 21a-i, 22a-f, and 26g-i were doubled.

Vasodilator-stimulated phosphoprotein serine 239 phosphorylation as a sensitive monitor of defective nitric oxide/cGMP signaling and endothelial dysfunction

Studies with cGMP-dependent protein kinase I (cGK-I)-deficient human cells and mice demonstrated that cGK-I ablation completely disrupts the NO/cGMP pathway in vascular tissue, which indicates a key role of this protein kinase as a mediator of the NO/cGMP action. Analysis of the vasodilator-stimulated phosphoprotein phosphorylated at serine 239 (P-VASP) is a useful tool to monitor cGK-I activation in platelets and cultured endothelial and smooth muscle cells. Therefore, we investigated whether endothelial dysfunction and/or vascular NO bioavailability is reflected by decreased vessel wall P-VASP and whether improvement of endothelial dysfunction restores this P-VASP. Incubation of aortic tissue from New Zealand White Rabbits with the NOS inhibitor N:(G)-nitro-Ld-arginine and endothelial removal strikingly reduced P-VASP. Oxidative stress induced by inhibition of CuZn superoxide dismutase increased superoxide and decreased P-VASP. Endothelial dysfunction in hyperlipidemic Watanabe rabbits (WHHL) was associated with increased vascular superoxide and with decreased P-VASP. Treatment of WHHL with AT(1) receptor blockade improved endothelial dysfunction, reduced vascular superoxide, increased vascular NO bioavailability, and increased P-VASP. Therefore, the level of vessel P-VASP closely follows changes in endothelial function and vascular oxidative stress. P-VASP is suggested to represent a novel biochemical marker for monitoring the NO-stimulated sGC/cGK-I pathway and endothelial integrity in vascular tissue.

Homologous functional expression of cryptic phaG from Pseudomonas oleovorans establishes the transacylase-mediated polyhydroxyalkanoate biosynthetic pathway

Various pseudomonads are capable of the synthesis of polyhydroxyalkanoate (PHA), composed of medium chain length (MCL) 3-hydroxy fatty acids (C6-C14), when grown on simple carbon sources such as, for example, gluconate or acetate. In Pseudomonas putida, the fatty acid de novo synthesis and PHA synthesis are linked by the transacylase PhaG. Southern hybridization experiments with digoxigenin-labeled phaG(Pp) from P. putida and genomic DNA from various pseudomonads indicate that phaG homologues are present in various other pseudomonads. Although P. oleovorans does not accumulate PHA(MCL) from non-related carbon sources, its genomic DNA reveals a strong hybridization signal. We employed PCR to amplify this phaG homologue. The respective PCR product comprising the coding region of phaG(Po) was cloned into pBBR1MCS-2, resulting in plasmid pBHR84. DNA sequencing revealed that putative PhaG(Po) from P. oleovorans exhibited about 95% amino acid sequence identity to PhaG(Pp) from P. putida. Reverse transcriptase-PCR analysis demonstrated that phaG(Po) was not transcribed even tinder inducing conditions, i.e. in the presence of gluconate as carbon source, whereas induction of phaG(Pp) transcription was obtained in P. putida. When octanoate was used as sole carbon source, only low levels of phaG mRNA were detected in P. putida. Plasmid pBHR84 complemented the phaG-negative mutant PhaG(N)-21 from P. putida. Interestingly, reintroduction of phaG(Po) under lac promoter control into the natural host P. oleovorans established PHA(MCL) synthesis from non-related carbon sources in this bacterium. These data indicated that phaG(Po) in P. oleovorans is not functionally expressed and does not exert its original function.

Substituent effects on two-center three-electron bonds and hydrogen bonds involving unsaturated organic functional groups and an ammonia radical cation--the resonance contribution

A theoretical investigation of the substituent effects on the two-center, three-electron (2c-3e) bond involved between unsaturated functional groups and an amine nitrogen is presented. The competitive hydrogen-bonded complexes are also studied. In both cases, the bond energies are found to be in the range of 20-30 kcal mol(-1). The variation of these energies is discussed with respect to the electron-donating effect of the substitutents, as well as with respect to the alpha-bonded atom of the organic functional group (O, S, NH). For the 2c-3e bonds, the results are discussed on the basis of the differences of the ionization potential (delta IP) of the separated fragments and can be rationalized through the valence bond theory. For the hydrogen bonds, the substituent influence is discussed by using the differences of the proton affinities (delta PA) of the substrates. The resonating nature of the hydrogen bond in these cationic systems is investigated and is found to account for most of the binding energy. Marcus theory is compared with the proposed resonating model.

The Pseudomonas aeruginosa phaG gene product is involved in the synthesis of polyhydroxyalkanoic acid consisting of medium-chain-length constituents from non-related carbon sources

We recently identified the phaG(Pp) gene encoding (R)-3-hydroxydecanoyl-ACP:CoA transacylase in Pseudomonas putida, which directly links the fatty acid de novo biosynthesis and polyhydroxyalkanoate (PHA) biosynthesis. An open reading frame (ORF) of which the deduced amino acid sequence shared about 57% identity with PhaG from P. putida was identified in the P. aeruginosa genome sequence. Its coding region (herein called phaG(Pa)) was amplified by PCR and cloned into the vector pBBR1MCS-2 under lac promoter control. The resulting plasmid pBHR88 mediated PHA synthesis contributing to about 13% of cellular dry weight from non-related carbon sources in the phaG(Pp)-negative mutant P. putida PhaG(N)-21. The PHA was composed of 5 mol% 3-hydroxydodecanoate, 61 mol% 3-hydroxydecanoate, 29 mol% 3-hydroxyoctanoate and 5 mol% 3-hydroxyhexanoate. Furthermore, an isogenic phaG(Pa) knock-out mutant of P. aeruginosa was constructed by gene replacement. The phaG(Pa) mutant did not show any difference in growth rate, but PHA accumulation from gluconate was decreased to about 40% of wild-type level, whereas from fatty acids wild-type level PHA accumulation was obtained. These data suggested that PhaG from P. aeruginosa exhibits 3-hydroxyacyl-ACP:CoA transacylase activity and strongly enhances the metabolic flux from fatty acid de novo synthesis towards PHA(MCL) synthesis. Therefore, a function could be assigned to the ORF present in the P. aeruginosa genome, and a second PhaG is now known.

Growth factors released into the coronary circulation after vascular injury promote proliferation of human vascular smooth muscle cells in culture

OBJECTIVES

This study sought to 1) assess in vivo release of platelet-derived growth factor (PDGF) and basic fibroblast growth factor (bFGF) into the coronary circulation after vascular injury in human subjects; and 2) evaluate mitogenic effects of PDGF and bFGF on the patient's own vascular smooth muscle cells (VSMCs).

BACKGROUND

Circumstantial evidence suggests involvement of PDGF and bFGF peptides in the neointimal response to vascular injury. To date, no study has shown biologically active growth factors within the coronary circulation after vascular injury in human subjects.

METHODS

In 18 patients, plasma PDGF AB, platelet factor 4 (PF4) and beta-thromboglobulin (beta-TG) levels were measured in coronary sinus blood obtained before and up to 30 min after angioplasty. In five patients undergoing atherectomy, coronary sinus serum was added to cultured VSMCs derived from atherectomy tissue to assess the mitogenic potential of the serum. Mitogenicity attributable to PDGF and bFGF was determined using neutralizing antibodies to these factors. PDGF A, PDGF B and bFGF were localized within the atherectomy tissue using immunocytochemical analysis.

RESULTS

Before angioplasty, PDGF AB, PF4 and beta-TG levels were elevated threefold in patients scheduled for angioplasty compared with those in control patients (p < 0.01). Within 5 min of angioplasty, PDGF AB levels increased twofold and returned toward preangioplasty levels at 30 min; PF4 and beta-TG levels remained elevated. Serum obtained at 30 min after atherectomy showed a sixfold increase in mitogenicity compared with preatherectomy serum (p = 0.01). This increase in mitogenicity was reduced by 20%, 40% and 65% in the presence of neutralizing antibodies to PDGF, bFGF and PDGF + bFGF, respectively. PDGF A, PDGF B and bFGF were visualized within the intima of the atherectomy tissue.

CONCLUSIONS

The change in plasma PDGF level is consistent with first-phase release of PDGF after vascular injury. The increase in mitogenicity of serum suggests that PDGF and bFGF are biologically active.

[Detection and diagnosis of small ocular misalignment with the Purkinje reflex pattern method]

BACKGROUND

Application test for an automatic classification strategy for ocular alignment data for the detection of ocular misalignment in strabismic patients.

METHODS

Photographic Purkinje Reflection Pattern Evaluation was used a) with a handheld device for the detection and measurement of ocular misalignments in near fixation (group 1, n = 64 strabismic patients) and b) with a stationary device for the detection and measurement of ocular misalignments in near fixation (group 2, n = 38 patients) and in distance fixation (group 3, n = 36 patients). The orthoptic diagnoses were mostly primary and secondary microtropia with manifest angles of strabismus from naught or 0.25 degrees to 3-4 degrees, with maximum angles up to 6-9 degrees. The ocular alignment data were classified using the computer based strabismus index procedure. This strategy relies on thresholds derived from means and standard deviations in orthotropic control populations. In this way the data sets were classified automatically as "no referral" or "referral". In addition, an automatic diagnosis of the type of misalignment was given and the results were compared to the orthoptic gold standard.

RESULTS

The sensitivity for the detection of a manifest ocular misalignment was a ca. 80% in group 1 and 2, and 90% in group 3, with specificities from 90% to 100%. All manifest angles of strabismus larger than 1 degree were correctly classified as "referral". There was good agreement between the diagnoses of the type of misalignment in most cases. Discrepancies were observed with very small ocular misalignments or with incomplete data sets, or they could be explained by a switch of fixation. The amount of the misalignment varied markedly as compared to the orthoptic measurement in a number of cases.

CONCLUSIONS

The examination allows for a detection of small manifest ocular misalignments with a very high sensitivity. The deviated eye and the type of the misalignment in the primary position are evaluated automatically by a data base computer algorithm. The differences between the measured angles of strabismus indicate that the photographic examination conditions and the orthoptic simultaneous prism and cover test conditions are not exactly alike. Purkinje Reflection Pattern Evaluation represents a step towards an examiner-independent measurement of the angle of strabismus.