Clinical and economic burden of organ damage among patients with systemic lupus erythematosus in a real-world setting in Germany

BACKGROUND

Systemic lupus erythematosus (SLE), a chronic multisystem autoimmune disease, carries high risk of organ damage and burden to healthcare systems. SLE disease modification aims to reduce disease activity with minimal treatment toxicity and preventing or minimizing organ damage development. This real-world study utilizing healthcare administrative claims data assessed organ damage development, associated costs and healthcare resource utilization (HCRU) in patients with SLE in Germany.

METHODS

Claims data from January 1, 2007, to December 31, 2017, were obtained from the Betriebskrankenkassen German Sickness Fund Database. Adults (> 18 years) with a confirmed SLE diagnosis between January 1, 2009, and December 31, 2014, (inclusion period) were included. The index date was calculated based on the first recorded SLE diagnosis during this period. Patients were propensity score-matched (1:3) to a comparator cohort without SLE by age, sex, and comorbidities (Charlson comorbidity index). Organ damage was identified using an algorithm developed based on conditions described in the Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index (SDI), using ICD-10-GM diagnostic codes, healthcare procedures, and/or treatments.

RESULTS

2121 patients with SLE and 6308 comparator patients were included (mean follow-up time: 6.4 years). Organ damage prevalence increased from 60.5% at baseline to 83.0% during 6 years of follow-up in all patients with SLE, while 17.0% of patients with SLE did not develop organ damage. Patients with newly confirmed SLE diagnosis without organ damage at baseline were nearly twice as likely to develop organ damage within 5 years versus the comparator cohort (52.0% vs. 27.0%). Total annual costs per patient-year for patients with SLE with organ damage were more than double those of patients with SLE without organ damage; both the number of inpatient admissions and length of stay were higher.

CONCLUSIONS

The application of a recently developed algorithm allowed us to use claims data to elucidate SLE organ damage, and its associated high clinical and economic burden, in a large, representative sample in Germany. To our knowledge, this is the first European analysis of its kind involving a broad cohort of patients with SLE treated in the routine care setting.

Real-World Burden of Immunosuppressant-Treated Lupus Nephritis: A German Claims Database Analysis

INTRODUCTION

This retrospective cohort study (GSK213737) aimed to characterize treatment patterns, healthcare resource utilization (HCRU), and costs in patients with lupus nephritis (LN) initiating immunosuppressant therapy in clinical practice in Germany, to better understand the full picture of the real-world burden of LN.

METHODS

Adult patients with LN who initiated mycophenolate mofetil (MMF), intravenous cyclophosphamide (CYC), azathioprine (AZA), tacrolimus, cyclosporin A, or rituximab therapy in 2011-2017 (index therapy) were identified from the Betriebskrankenkassen German Sickness Fund database. Treatment patterns, including immunosuppressant discontinuations, and therapy switches, were assessed (maximum follow-up 4 years). Corticosteroid use, HCRU, and total economic costs were also evaluated. HCRU and costs were compared with matched controls (individuals without systemic lupus erythematosus [SLE]/LN matched by age, sex, and baseline Charlson Comorbidity Index).

RESULTS

Among 334 patients with LN, the median (interquartile range) duration of index immunosuppressant therapy use was 380.5 (126, 1064) days. Of those patients with 4 years complete enrollment, 70.8% had ≥ 1 discontinuation and 28.8% switched therapy. While most patients (71.2%) received only one immunosuppressant, gaps in treatment were common. After 1 year of follow-up, 41.6% of patients had a prednisone-equivalent corticosteroid dose of ≥ 7.5 mg/day. Patients with LN had greater HCRU use for most categories assessed and increased mean total costs per person-year versus controls (€15,115.99 versus €4,081.88 in the first year of follow-up).

CONCLUSIONS

This real-world analysis demonstrated the considerable burden of immunosuppressant-treated LN in Germany, with a high rate of discontinuations, frequent use of high-dose corticosteroids, and substantial HCRU/costs.

Population estimates of obstructive and non-obstructive hypertrophic cardiomyopathy in the UK and Germany

Background

While numerous publications have estimated the prevalence of diagnosed hypertrophic cardiomyopathy (HCM), none have quantified the real-world proportion of obstructive and non-obstructive HCM using nationally representative data sources in any European countries.

Purpose

To estimate the prevalence of diagnosed HCM and its subtypes in the UK and Germany.

Methods

Patients with HCM were identified in the UK from 01 Apr 2009 to 30 Oct 2020 and Germany from 2011 to 2019. UK patients with HCM were identified using electronic health records from the Clinical Practice Research Datalink (CPRD) primary care data linked with Hospital Episode Statistics (HES) secondary care data using ICD-10 (I42.1, I42.2), Read, Medcode, SNOMED, and OPCS codes. German patients with HCM were identified using a nationally representative administrative claims data pool (WIG2 Benchmark database) from several German Statutory Health Insurance (SHI)-insurances using ICD-10 and OPS codes. Obstructive HCM was identified as any obstructive HCM diagnosis, any HCM diagnosis with septal reduction therapy, and any HCM diagnosis and left ventricular outflow tract obstruction (LVOTO; not in German claims data). Non-obstructive HCM was any non-obstructive or unspecified HCM diagnosis without evidence of any obstructive HCM. Annual prevalence was calculated for each year in the respective study periods and average annual prevalence across the study period.

Results

The average annual prevalence rate of HCM was 4.15/10,000 in the UK and 8.61/10,000 in Germany, while the average annual prevalence rate of obstructive HCM was 2.84/10,000 in the UK and 4.18/10,000 in Germany (Table). The proportion of HCM that was obstructive HCM was 68% in the UK and 49% in Germany. The prevalence rates of diagnosed HCM and obstructive HCM tended to increase over time (Figure).

Conclusion

The prevalence of HCM, obstructive HCM and the proportion of HCM that is obstructive varied between the UK and Germany. The prevalence of HCM was generally consistent with previously published estimates. Although there are limitations with coding in administrative data, it is important to differentiate obstructive HCM from non-obstructive HCM given their unique treatments and disease progression and management, especially since at least 49–68% of HCM is obstructive.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): Bristol Myers-Squibb

MO505: Prevalence of Lupus Nephritis Among Patients With Systemic Lupus Erythematosus In Germany

BACKGROUND AND AIMS

Lupus nephritis (LN) is the most common severe manifestation of systemic lupus erythematosus (SLE) and can lead to end-stage renal disease and death. However, there are limited data to contextualize the burden of LN in Germany, with no published studies using national claims data. This cross-sectional study aimed to estimate the annual prevalence of SLE and LN from 2011–17 using claims data from the Betriebskrankenkassen (BKK) German Sickness Fund Database.

METHOD

For each study year (2011–17), three patient populations were identified using International Classification of Diseases, Tenth Revision, German Modification (ICD-10-GM) codes: (1) Patients with SLE (≥1 SLE inpatient claim or ≥1 outpatient claim with a confirmatory claim in a separate quarter within ± 3 years); (2) Patients with LN, sensitive definition (based on the presence of SLE [as above] with ≥ 1 nephritis claim within ± 1 year from the initial SLE claim) and (3) Patients with LN, specific definition (based on the presence of SLE [as above] with ≥ 2 nephritis claims in separate quarters within ± 1 year from the initial SLE claim). For each year, the annual prevalence of SLE and LN/100 000 was estimated by dividing the number of patients identified in each population by the number of individuals insured in the database in that year. The proportion of SLE patients with LN was also estimated. To estimate the total number of patients with SLE and LN in Germany by age and sex standardization, the German statutory health insurance (SHI) system (covering 87% of the German population) was used to extrapolate from the prevalence calculated in the BKK database.

RESULTS

Approximately 5 million patients were insured in the BKK database between 2011–17; the ratio of insured males to females was ∼1:1 throughout the study period. The annual prevalence of SLE and LN/100 000 increased from 2011 (SLE, 37.68; LN sensitive, 12.79; LN specific, 9.99) to 2017 (SLE, 54.74; LN sensitive, 19.06; LN specific, 15.16) (Fig. 1). In 2017, the ratio of males to females/100 000 patients was ∼1:5.5 for the SLE cohort, 1:4.5 for the LN-sensitive cohort and 1:4.4 for the LN-specific cohort.

The proportion of SLE patients with LN remained consistent across the study period, ranging from 26.51% (specific definition) and 33.96% (sensitive definition) in 2011 to 27.69% and 34.82%, respectively, in 2017.

When extrapolating the prevalence estimates to the wider German SHI system, the estimated number of SLE patients was >41 000 in 2017, with the total LN patient population ranging from 11 515 (specific definition) to 14 483 (sensitive definition) (Fig. 2).

CONCLUSION

The prevalence of LN increased between 2011 and 2017 among patients insured in the BKK database and is estimated to impact >11 000 patients in the wider German SHI system. Limitations include an absence of renal biopsy information and the inability to distinguish patients with active nephritis from those with historical or inactive LN based on clinical parameters. Nonetheless, these data highlight the prevalence of LN among patients with SLE and the need for effective screening and disease management to improve patient outcomes. Further work to understand the treatment and economic burden of LN among patients with SLE in Germany is ongoing.

KIN3 impacts arbuscular mycorrhizal symbiosis and promotes fungal colonisation in Medicago truncatula

Arbuscular mycorrhizal fungi help their host plant in the acquisition of nutrients, and this association is itself impacted by soil nutrient levels. High phosphorus levels inhibit the symbiosis, whereas high nitrogen levels enhance it. The genetic mechanisms regulating the symbiosis in response to soil nutrients are poorly understood. Here, we characterised the symbiotic phenotypes in four Medicago truncatula Tnt1-insertion mutants affected in arbuscular mycorrhizal colonisation. We located their Tnt1 insertions and identified alleles for two genes known to be involved in mycorrhization, RAM1 and KIN3. We compared the effects of the kin3-2 and ram1-4 mutations on gene expression, revealing that the two genes alter the expression of overlapping but not identical gene sets, suggesting that RAM1 acts upstream of KIN3. Additionally, KIN3 appears to be involved in the suppression of plant defences in response to the fungal symbiont. KIN3 is located on the endoplasmic reticulum of arbuscule-containing cortical cells, and kin3-2 mutants plants hosted significantly fewer arbuscules than the wild type. KIN3 plays an essential role in the symbiotic response to soil nitrogen levels, as, contrary to wild-type plants, the kin3-2 mutant did not exhibit increased root colonisation under high nitrogen.

The speed limit of optoelectronics

Light-field driven charge motion links semiconductor technology to electric fields with attosecond temporal control. Motivated by ultimate-speed electron-based signal processing, strong-field excitation has been identified viable for the ultrafast manipulation of a solid's electronic properties but found to evoke perplexing post-excitation dynamics. Here, we report on single-photon-populating the conduction band of a wide-gap dielectric within approximately one femtosecond. We control the subsequent Bloch wavepacket motion with the electric field of visible light. The resulting current allows sampling optical fields and tracking charge motion driven by optical signals. Our approach utilizes a large fraction of the conduction-band bandwidth to maximize operating speed. We identify population transfer to adjacent bands and the associated group velocity inversion as the mechanism ultimately limiting how fast electric currents can be controlled in solids. Our results imply a fundamental limit for classical signal processing and suggest the feasibility of solid-state optoelectronics up to 1 PHz frequency.

Slow light nanocoatings for ultrashort pulse compression

Transparent materials do not absorb light but have profound influence on the phase evolution of transmitted radiation. One consequence is chromatic dispersion, i.e., light of different frequencies travels at different velocities, causing ultrashort laser pulses to elongate in time while propagating. Here we experimentally demonstrate ultrathin nanostructured coatings that resolve this challenge: we tailor the dispersion of silicon nanopillar arrays such that they temporally reshape pulses upon transmission using slow light effects and act as ultrashort laser pulse compressors. The coatings induce anomalous group delay dispersion in the visible to near-infrared spectral region around 800 nm wavelength over an 80 nm bandwidth. We characterize the arrays' performance in the spectral domain via white light interferometry and directly demonstrate the temporal compression of femtosecond laser pulses. Applying these coatings to conventional optics renders them ultrashort pulse compatible and suitable for a wide range of applications.

Broadband phase-shifting mirrors for ultrafast lasers

Metal-dielectric phase-shifting multilayer optical elements have been developed, providing broadband, virtually dispersion-free polarization manipulation down to the few-cycle level. These optical elements are Ag/Al₂O₃ mirrors that operate in the spectral range from 500 to 100 nm, exhibiting reflectance higher than 95%, and a differential phase shift between the s- and p-polarization of about 90° distributed over four bounces. The mirrors have been designed, produced, and reliably characterized based on spectral photometric and ellipsometric data using a non-parametric approach as well as a multi-oscillator model. The optical elements were implemented into a few-cycle laser system, where they transformed linearly polarized few-cycle light pulses to circular polarization.

Carrier frequency tuning of few-cycle light pulses by a broadband attenuating mirror

We demonstrate the performance of a novel multilayer dielectric reflective thin-film attenuator capable of reshaping the super-octave spectrum of near-single-cycle visible laser pulses without deteriorating the phase properties of the reflected light. These novel broadband attenuating mirrors reshape in a virtually dispersion-free manner the incident spectrum such that the carrier wavelength of the reflected pulses shifts from ∼700  nm (E_γ=1.77  eV) to ∼540  nm (E_γ=2.25  eV) or beyond while maintaining their initial near-single-cycle pulse duration. This constitutes a viable approach to convert a number of established few-cycle ultrafast laser systems into sources with a selectable excitation wavelength to meet the requirements of single-color/multicolor high temporal resolution spectroscopic experiments.

Study of filamentation with a high power high repetition rate ps laser at 1.03 µm

We study the propagation of intense, high repetition rate laser pulses of picosecond duration at 1.03 µm central wavelength through air. Evidence of filamentation is obtained from measurements of the beam profile as a function of distance, from photoemission imaging and from spatially resolved sonometric recordings. Good agreement is found with numerical simulations. Simulations reveal an important self shortening of the pulse duration, suggesting that laser pulses with few optical cycles could be obtained via double filamentation. An important lowering of the voltage required to induce guided electric discharges between charged electrodes is measured at high laser pulse repetition rate.

Overexpression of the potassium channel TPKb in small vacuoles confers osmotic and drought tolerance to rice

Potassium (K(+) ) is the most important cationic nutrient for all living organisms. Vacuolar two-pore K(+) (TPK) channels are important players in the regulation of cellular levels of K(+) but have not been characterised in rice. In order to assess the role of OsTPKb, a K(+) selective ion channel predominantly expressed in the tonoplast of small vacuoles, we generated overexpressing (OX) lines using a constitutive promoter and compared their phenotypes with control plants. Relative to control plants, OX lines showed better growth when exposed to low-K(+) or water stress conditions. K(+) uptake was greater in OX lines which may be driven by increased AKT1 and HAK1 activity. The enhanced K(+) uptake led to tissue K(+) levels that were raised in roots and shoots. Furthermore, energy dispersive X-ray (EDX) analyses showed a higher cytoplasm: vacuole K(+) ratio which is likely to contribute to the increased stress tolerance. In all, the data suggest that TPKb can alter the K(+) status of small vacuoles, which is important for general cellular K(+) homeostasis which, in turn, affects stress tolerance.

A H+-ATPase That Energizes Nutrient Uptake during Mycorrhizal Symbioses in Rice and Medicago truncatula

Most plant species form symbioses with arbuscular mycorrhizal (AM) fungi, which facilitate the uptake of mineral nutrients such as phosphate from the soil. Several transporters, particularly proton-coupled phosphate transporters, have been identified on both the plant and fungal membranes and contribute to delivering phosphate from fungi to plants. The mechanism of nutrient exchange has been studied in plants during mycorrhizal colonization, but the source of the electrochemical proton gradient that drives nutrient exchange is not known. Here, we show that plasma membrane H+-ATPases that are specifically induced in arbuscule-containing cells are required for enhanced proton pumping activity in membrane vesicles from AM-colonized roots of rice (Oryza sativa) and Medicago truncatula. Mutation of the H+-ATPases reduced arbuscule size and impaired nutrient uptake by the host plant through the mycorrhizal symbiosis. Overexpression of the H+-ATPase Os-HA1 increased both phosphate uptake and the plasma membrane potential, suggesting that this H+-ATPase plays a key role in energizing the periarbuscular membrane, thereby facilitating nutrient exchange in arbusculated plant cells.

RAM1 and RAM2 function and expression during arbuscular mycorrhizal symbiosis and Aphanomyces euteiches colonization

The establishment of the symbiotic interaction between plants and arbuscular mycorrhizal (AM) fungi requires a very tight molecular dialogue. Most of the known plant genes necessary for this process are also required for nodulation in legume plants and only very recently genes specifically required for AM symbiosis have been described. Among them we identified RAM (Reduced Arbuscular Mycorrhization)1 and RAM2, a GRAS transcription factor and a GPAT respectively, which are critical for the induction of hyphopodia formation in AM fungi. RAM2 function is also required for appressoria formation by the pathogen Phytophtora palmivora. Here we investigated the activity of RAM1 and RAM2 promoters during mycorrhization and the role of RAM1 and RAM2 during infection by the root pathogen Aphanomyces euteiches. pRAM1 is activated without cell type specificity before hyphopodia formation, while pRAM2 is specifically active in arbusculated cells providing evidence for a potential function of cutin momomers in the regulation of arbuscule formation. Furthermore, consistent with what we observed with Phytophtora, RAM2 but not RAM 1 is required during Aphanomyces euteiches infection.

Protocols for growing plant symbioses; mycorrhiza

Arbuscular mycorrhizal symbiosis is receiving increased attention as a potential contributor to sustainable crop plant nutrition. This chapter details a set of protocols for plant growth to study the development and physiology of the arbuscular mycorrhizal symbiosis, and how to establish root organ cultures for the production of axenic inoculum.

Impact of temporal, spatial and cascaded effects on the pulse formation in ultra-broadband parametric amplifiers

A 2 + 1 dimensional nonlinear pulse propagation model is presented, illustrating the weighting of different effects for the parametric amplification of ultra-broadband spectra in different regimes of energy scaling. Typical features in the distribution of intensity and phase of state-of-the-art OPA-systems can be understood by cascaded spatial and temporal effects.

A common signaling process that promotes mycorrhizal and oomycete colonization of plants

The symbiotic association between plants and arbuscular mycorrhizal fungi is almost ubiquitous within the plant kingdom, and the early stages of the association are controlled by plant-derived strigolactones acting as a signal to the fungus in the rhizosphere and lipochito-oligosaccharides acting as fungal signals to the plant. Hyphopodia form at the root surface, allowing the initial invasion, and this is analogous to appressoria, infection structures of pathogenic fungi and oomycetes. Here, we characterize RAM2, a gene of Medicago truncatula required for colonization of the root by mycorrhizal fungi, which is necessary for appropriate hyphopodia and arbuscule formation. RAM2 encodes a glycerol-3-phosphate acyl transferase (GPAT) and is involved in the production of cutin monomers. Plants defective in RAM2 are unable to be colonized by arbuscular mycorrhizal fungi but also show defects in colonization by an oomycete pathogen, with the absence of appressoria formation. RAM2 defines a direct signaling function, because exogenous addition of the C16 aliphatic fatty acids associated with cutin are sufficient to promote hyphopodia/appressoria formation. Thus, cutin monomers act as plant signals that promote colonization by arbuscular mycorrhizal fungi, and this signaling function has been recruited by pathogenic oomycetes to facilitate their own invasion.

High power ultra-widely tuneable femtosecond pulses from a non-collinear optical parametric oscillator (NOPO)

We present an ultra-widely tunable non-collinear optical parametric oscillator with an average output power of more than 3 W and a repetition frequency of 34 MHz. The system is pumped by the second harmonic of a femtosecond Yb:KLu(WO4)2 thin-disk laser oscillator. The wavelength of the signal pulse can be rapidly tuned over a wide range from the visible to the NIR just by scanning the resonator length.

Vapyrin, a gene essential for intracellular progression of arbuscular mycorrhizal symbiosis, is also essential for infection by rhizobia in the nodule symbiosis of Medicago truncatula

Intracellular invasion of root cells is required for the establishment of successful endosymbioses in legumes of both arbuscular mycorrhizal (AM) fungi and rhizobial bacteria. In both interactions a requirement for successful entry is the activation of a common signalling pathway that includes five genes required to generate calcium oscillations and two genes required for the perception of the calcium response. Recently, it has been discovered that in Medicago truncatula, the Vapyrin (VPY) gene is essential for the establishment of the arbuscular mycorrhizal symbiosis. Here, we show by analyses of mutants that the same gene is also required for rhizobial colonization and nodulation. VPY encodes a protein featuring a Major Sperm Protein domain, typically featured on proteins involved in membrane trafficking and biogenesis, and a series of ankyrin repeats. Plants mutated in this gene have abnormal rhizobial infection threads and fewer nodules, and in the case of interactions with AM fungi, epidermal penetration defects and aborted arbuscule formation. Calcium spiking in root hairs in response to supplied Nod factors is intact in the vpy-1 mutant. This, and the elevation of VPY transcripts upon application of Nod factors which we show to be dependent on NFP, DMI1, and DMI3, indicates that VPY acts downstream of the common signalling pathway.

Route to attosecond nonlinear spectroscopy

We demonstrate generation of coherent microjoule-scale, low-order harmonic supercontinua in the deep and vacuum ultraviolet (4-9 eV), resulting from the nonlinear transformations of near-single-cycle laser pulses in a gas cell. We show theoretically that their formation is connected to a novel nonlinear regime, holding promise for the generation of powerful deep-UV and vacuum ultraviolet subfemtosecond pulses. Our work opens the route to pump-probe spectroscopy of subfemtosecond-scale valence-shell phenomena in atoms, molecules, and condensed matter.

Versatile apparatus for attosecond metrology and spectroscopy

We present the AS-2 Attosecond Beamline at the Joint Laboratory for Attosecond Physics of the Max-Planck-Institut für Quantenoptik and Ludwig-Maximilians-Universität for time resolved pump/probe experiments with attosecond resolution. High harmonic generation and subsequent filtering of the generated extreme ultraviolet (XUV) continuum by means of metal filters and XUV multilayer mirrors serve for the generation of isolated attosecond laser pulses. After high harmonic generation, the remaining fundamental laser pulse is spatially separated from the attosecond XUV pulse, to what is to our knowledge for the first time, by means of a perforated mirror in a Mach-Zehnder interferometer. Active stabilization of this interferometer guarantees the necessary temporal resolution for tracking attosecond dynamics in real time. As a proof-of-principle, photoelectron streaking experiments are performed and experimental techniques for their realization are summarized. Finally we highlight the potential of the presented beamline system for future experiments in comparison with previously demonstrated attosecond beamlines.

Circadian plasticity in photoreceptor cells controls visual coding efficiency in Drosophila melanogaster

In the fly Drosophila melanogaster, neuronal plasticity of synaptic terminals in the first optic neuropil, or lamina, depends on early visual experience within a critical period after eclosion [1]. The current study revealed two additional and parallel mechanisms involved in this type of synaptic terminal plasticity. First, an endogenous circadian rhythm causes daily oscillations in the volume of photoreceptor cell terminals. Second, daily visual experience precisely modulates the circadian time course and amplitude of the volume oscillations that the photoreceptor-cell terminals undergo. Both mechanisms are separable in their molecular basis. We suggest that the described neuronal plasticity in Drosophila ensures continuous optimal performance of the visual system over the course of a 24 h-day. Moreover, the sensory system of Drosophila cannot only account for predictable, but also for acute, environmental changes. The volumetric changes in the synaptic terminals of photoreceptor cells are accompanied by circadian and light-induced changes of presynaptic ribbons as well as extensions of epithelial glial cells into the photoreceptor terminals, suggesting that the architecture of the lamina is altered by both visual exposure and the circadian clock. Clock-mutant analysis and the rescue of PER protein rhythmicity exclusively in all R1-6 cells revealed that photoreceptor-cell plasticity is autonomous and sufficient to control visual behavior. The strength of a visually guided behavior, the optomotor turning response, co-varies with synaptic-terminal volume oscillations of photoreceptor cells when elicited at low light levels. Our results show that behaviorally relevant adaptive processing of visual information is performed, in part, at the level of visual input level.

Three-dimensional momentum imaging of electron wave packet interference in few-cycle laser pulses

Using a reaction microscope, three-dimensional (3D) electron (and ion) momentum (P) spectra have been recorded for carrier-envelope-phase (CEP) stabilized few-cycle ( approximately 5 fs), intense ( approximately 4 x 10(14) W/cm2) laser pulses (740 nm) impinging on He. Preferential emission of low-energy electrons (E(e)<15 eV) to either hemisphere is observed as a function of the CEP. Clear interference patterns emerge in P space at CEPs with maximum asymmetry, interpreted as attosecond interferences of rescattered and directly emitted electron wave packets by means of a simple model.

Intense few-cycle light pulses in the deep ultraviolet

We demonstrate that nonlinear frequency upconversion of few-cycle near-infrared (NIR) laser pulses, by means of harmonic generation in noble gases, is a promising approach for extending cutting-edge, few-cycle ultrafast technology into the deep ultraviolet and beyond, without the need for UV dispersion control. In our experiment, we generate 3.7-fs pulses in the deep UV (approximately 4.6 eV) with adjustable polarization and gigawatt-scale peak power. We demonstrate that the implementation of this concept with a quasi-monocycle driver offers the potential for advancing UV pulse generation towards the 1-fs frontier.

Ultrabroadband, coherent light source based on self-channeling of few-cycle pulses in helium

Self-channeling of few-cycle laser pulses in helium at high pressure generates coherent light supercontinua spanning the range of 270-1000 nm, with the highest efficiency demonstrated to date. Our results open the door to the synthesis of powerful light waveforms shaped within the carrier field oscillation cycle and hold promise for the generation of pulses at the single-cycle limit.

Medicago truncatula NIN is essential for rhizobial-independent nodule organogenesis induced by autoactive calcium/calmodulin-dependent protein kinase

The symbiotic association between legumes and nitrogen-fixing bacteria collectively known as rhizobia results in the formation of a unique plant root organ called the nodule. This process is initiated following the perception of rhizobial nodulation factors by the host plant. Nod factor (NF)-stimulated plant responses, including nodulation-specific gene expression, is mediated by the NF signaling pathway. Plant mutants in this pathway are unable to nodulate. We describe here the cloning and characterization of two mutant alleles of the Medicago truncatula ortholog of the Lotus japonicus and pea (Pisum sativum) NIN gene. The Mtnin mutants undergo excessive root hair curling but are impaired in infection and fail to form nodules following inoculation with Sinorhizobium meliloti. Our investigation of early NF-induced gene expression using the reporter fusion ENOD11::GUS in the Mtnin-1 mutant demonstrates that MtNIN is not essential for early NF signaling but may negatively regulate the spatial pattern of ENOD11 expression. It was recently shown that an autoactive form of a nodulation-specific calcium/calmodulin-dependent protein kinase is sufficient to induce nodule organogenesis in the absence of rhizobia. We show here that MtNIN is essential for autoactive calcium/calmodulin-dependent protein kinase-induced nodule organogenesis. The non-nodulating hcl mutant has a similar phenotype to Mtnin, but we demonstrate that HCL is not required in this process. Based on our data, we suggest that MtNIN functions downstream of the early NF signaling pathway to coordinate and regulate the correct temporal and spatial formation of root nodules.

Observation of a transition in the water-nanoparticle formation process at 167K

Rapid-scan Fourier transform infrared spectroscopy of the vapor/solid formation process of water nanoparticles in the 180-140 K temperature range at thermal-equilibrium conditions is reported. At 167 K a transition in the formation process was observed: the particle volume quintuples and the particle formation time triples within a temperature interval of +/-0.4 K caused by the temperature control. The authors interpret this behavior by an abrupt change in the nucleation rate of the H2O monomers in He buffer gas kept at 167 K and 200 mbar. A size and shape analysis of the particles during the formation process was carried out by application of the discrete dipole approximation method which delivers excellent accordance between experimental and calculated mid-IR spectra. Compared to other compact shapes (cube, prolate ellipsoid, and hexagonal prism) the ideal spherical shape fits the experimental spectra best. A distinct change in shape by particle conversion or agglomeration could be excluded to be involved in the formation process. As a possible explanation of the observed phenomenon, a transition from vapor/liquid/solid to vapor/solid nucleation with decreasing temperature is considered which was recently theoretically predicted by van Dongen and co-workers [J. Chem. Phys. 117, 5647 (2002); private communication; J. Chem. Phys. 120, 6314 (2004)].

Attosecond real-time observation of electron tunnelling in atoms

Atoms exposed to intense light lose one or more electrons and become ions. In strong fields, the process is predicted to occur via tunnelling through the binding potential that is suppressed by the light field near the peaks of its oscillations. Here we report the real-time observation of this most elementary step in strong-field interactions: light-induced electron tunnelling. The process is found to deplete atomic bound states in sharp steps lasting several hundred attoseconds. This suggests a new technique, attosecond tunnelling, for probing short-lived, transient states of atoms or molecules with high temporal resolution. The utility of attosecond tunnelling is demonstrated by capturing multi-electron excitation (shake-up) and relaxation (cascaded Auger decay) processes with subfemtosecond resolution.

Molecular cloning of a bifunctional beta-xylosidase/alpha-L-arabinosidase from alfalfa roots: heterologous expression in Medicago truncatula and substrate specificity of the purified enzyme

Glycoside hydrolases are often members of a multigene family, suggesting individual roles for each isoenzyme. Various extracellular glycoside hydrolases have an important but poorly understood function in remodelling the cell wall during plant growth. Here, MsXyl1, a concanavalin A-binding protein from alfalfa (Medicago sativa L.) belonging to the glycoside hydrolase family 3 (beta-D-xylosidase branch) is characterized. Transcripts of MsXyl1 were detected in roots (particularly root tips), root nodules, and flowers. MsXyl1 under the control of the CaMV 35S promoter was expressed in the model legume Medicago truncatula (Gaertner). Concanavalin A-binding proteins from the transgenic plants exhibited 5-8-fold increased activities towards three p-nitrophenyl (PNP) glycosides, namely PNP-beta-D-xyloside, PNP-alpha-L-arabinofuranoside, and PNP-alpha-L-arabinopyranoside. An antiserum raised against a synthetic peptide recognized MsXyl1, which was processed to a 65 kDa form. To characterize the substrate specificity of MsXyl1, the recombinant protein was purified from transgenic M. truncatula leaves by concanavalin A and anion chromatography. MsXyl1cleaved beta-1,4-linked D-xylo-oligosaccharides and alpha-1,5-linked L-arabino-oligosaccharides. Arabinoxylan (from wheat) and arabinan (from sugar beet) were substrates for MsXyl1, whereas xylan (from oat spelts) was resistant to degradation. Furthermore, MsXyl1 released xylose and arabinose from cell wall polysaccharides isolated from alfalfa roots. These data suggest that MsXyl1 is a multifunctional beta-xylosidase/alpha-L-arabinofuranosidase/alpha-L-arabinopyranosidase implicated in cell wall turnover of arabinose and xylose, particularly in rapidly growing root tips. Moreover, the findings of this study demonstrate that stable transgenic M. truncatula plants serve as an excellent expression system for purification and characterization of proteins.

Control of Electron Localization in Molecular Dissociation

We demonstrated how the subcycle evolution of the electric field of light can be used to control the motion of bound electrons. Results are presented for the dissociative ionization of deuterium molecules (D2 --> D+ + D), where asymmetric ejection of the ionic fragment reveals that light-driven intramolecular electronic motion before dissociation localizes the electron on one of the two D+ ions in a controlled way. The results extend subfemtosecond electron control to molecules and provide evidence of its usefulness in controlling reaction dynamics.

Stimulation of serum- and glucocorticoid-regulated kinase-1 gene expression by endothelin-1

The serum- and glucocorticoid-regulated kinase-1 (SGK1) participates in the regulation of sodium homeostasis and blood pressure by mineralocorticoids. Aldosterone rapidly induces SGK1 transcription, which contributes to the activation of renal epithelial sodium channels. Another important regulator of blood pressure is the vasoactive hormone endothelin-1 (ET-1) that is systemically upregulated in chronic renal failure. In the present study, we investigated whether ET-1 modulates SGK1 expression, and thereby might explain some of its hypertensive effects. As assessed by real-time PCR analysis, ET-1 triggered the rapid increase of SGK1 mRNA levels in A-10 smooth muscle cells and also in intact aortas of adult rats. In A-10 cells transcriptional activation was associated with a more than 6-fold upregulation of SGK1 protein expression and in similar range as found after treatment with aldosterone. A stimulatory effect of ET-1 was not only observed in isolated cells, but also in an animal model. Upon subtotal nephrectomy (SNX) of rats, myocardial ET-1 levels strongly increased, which was followed by a more than 2-fold induction of SGK1 expression in the left ventricle. The myocardial upregulation of SGK1 was completely abrogated by a specific ET(A) receptor antagonist, thereby substantiating the in vivo role of ET-1 in SGK1 expression. Thus, these data demonstrate that ET-1 increases expression of SGK1 in vivo and in vitro, and therefore indicate that SGK1 upregulation might be involved in ET-1-dependent regulation of blood pressure and cardiac modelling during mild renal failure.

Modification of a continuous flow method for analysis of trace amounts of nitrate in iron-rich sediment pore-waters of mine pit lakes

Nitrate was analysed in pore-waters with high ionic strength. Extremely high concentrations of dissolved ferrous iron interfere common analytical methods. The automatic photometrical procedure based on the cadmium reduction method is often used for analysis of nitrate in water samples (continuous flow analysis CFA). An integrated dialysis usually serves for sample dilution and (or) sample purification (from particles). Iron was precipitated as iron hydroxide due to the imidazole buffer system (pH 7.5). The dialysis membrane is an effective barrier for iron hydroxide particles to prevent interferences within the cadmium column or the flow-cell. However, dialysis membrane is blocked successively after analysis of several iron-rich pore-water samples by agglomeration of precipitated iron. The blocking of nitrate diffusion through the dialysis membrane is tantamount to a decrease of analytical sensitivity to recognise by decreasing photometrical extinction. Minimising the iron deposition within the dialyser solved the problem. A simple modification of the CFA apparatus was found to keep the analytical sensitivity nearly constant: The mixing coil for the imidazole buffer was considerably elongated. Nearly all iron hydroxide was deposited at the glass coil surface installed before the dialyser. At least 50 iron-rich samples could be analysed within one sample queue with a loss of sensitivity <10%. The recovery of nitrate was about 95%, demonstrated by spiking experiments.

Endothelin-1 increases serum-glucocorticoid-regulated kinase-1 expression in smooth muscle cells

The mechanism of salt-sensitive hypertension is not fully understood. Several studies point to a possible role of endothelin (ET)-1 in this form of hypertension. Serum-regulated and glucocorticoid-regulated kinase-1 (SGK1) mediates trafficking of the renal epithelial sodium channel. The aim of the study was to find out whether ET-1 regulates SGK1. Rat smooth muscle cells were incubated with ET-1 (10(-7) M, 0-120 minutes). After 30 minutes a significant increase in SGK1 mRNA was found (122 +/- 4.2%), and a maximum was reached after 120 minutes (217 +/- 7.6%). Incubation of smooth muscle cells with ET-1 (10(-7) mol/L) in the presence of an ETA receptor antagonist inhibited SGK1 gene transcription (93 +/- 3.7%). Western blot analysis showed a time-dependent increase in SGK1 protein in smooth muscle cells. These data indicate that ET-1 increases SKG1 mRNA and protein concentration. Inhibition of ET-1 by ET antagonism prevented a SGK1 increase. Therefore, ET antagonism might influence blood pressure by regulating the sodium balance through reducing SGK1 gene expression.

How alfalfa root hairs discriminate between Nod factors and oligochitin elicitors

Using ion-selective microelectrodes, the problem of how signals coming from symbiotic partners or from potential microbial intruders are distinguished was investigated on root hairs of alfalfa (Medicago sativa). The Nod factor, NodRm-IV(C16:2,S), was used to trigger the symbiotic signal and (GlcNAc)(8) was selected from (GlcNAc)(4-8), to elicit defense-related reactions. To both compounds, root hairs responded with initial transient depolarizations and alkalinizations, which were followed by a hyperpolarization and external acidification in the presence of (GlcNAc)(8). We propose that alfalfa recognizes tetrameric Nod factors and N-acetylchitooligosaccharides (n = 4-8) with separate perception sites: (a) (GlcNAc)(4) and (GlcNAc)(6) reduced the depolarization response to (GlcNAc)(8), but not to NodRm-IV(C16:2, S); and (b) depolarization and external alkalization were enhanced when NodRm-IV(C16:2,S) and (GlcNAc)(8) were added jointly without preincubation. We suggest further that changes in cytosolic pH and Ca(2+) are key events in the transduction, as well as in the discrimination of signals leading to symbiotic responses or defense-related reactions. To (GlcNAc)(8), cells responded with a cytosolic acidification, and they responded to NodRm-IV(C16:2,S) with a sustained alkalinization. When both agents were added jointly, the cytosol first alkalized and then acidified. (GlcNAc)(8) and NodRm-IV(C16:2,S) transiently increased cytosolic Ca(2+) activity, whereby the response to (GlcNAc)(8) exceeded the one to NodRm-IV(C16:2,S) by at least a factor of two.

Nod factors of Rhizobium leguminosarum bv. viciae and their fucosylated derivatives stimulate a nod factor cleaving activity in pea roots and are hydrolyzed in vitro by plant chitinases at different rates

Nod factors (NFs) are rhizobial lipo-chitooligosaccharide signals that trigger root nodule development in legumes. Modifications of NF structures influence their biological activity and affect their degradation by plant chitinases. Nodulation of certain pea cultivars by Rhizobium leguminosarum bv. viciae requires modification of NFs at the reducing end by either an O-acetyl or a fucosyl group. Fucosylated NFs were produced by an in vitro reaction with NodZ fucosyltransferase and purified. Their biological activity on pea was tested by measuring their capacity to stimulate the activity of a hydrolase that cleaves NFs. Nonmodified and fucosylated NFs displayed this activity at nano- to picomolar concentrations, while a sulfated NF from Sinorhizobium meliloti was inactive. In an additional series of experiments, the stability of non-modified and fucosylated NFs in the presence of purified tobacco chitinases was compared. The presence of the fucosyl group affected the degradation rates and the accessibility of specific cleavage sites on the chitooligosaccharide backbone. These results suggest that the fucosyl group in NFs also weakens the interaction of NFs with certain chitinases or chitinase-related proteins in pea roots.

N-deacetylation of Sinorhizobium meliloti Nod factors increases their stability in the Medicago sativa rhizosphere and decreases their biological activity

Nod factors excreted by rhizobia are signal molecules that consist of a chitin oligomer backbone linked with a fatty acid at the nonreducing end. Modifications of the Nod factor structures influence their stability in the rhizosphere and their biological activity. To test the function of N-acetyl groups in Nod factors, NodSm-IV(C16:2,S) from Sinorhizobium meliloti was enzymatically N-deacetylated in vitro with purified chitin deacetylase from Colletotrichum lindemuthianum. A family of partially and completely deacetylated derivatives was produced and purified. The most abundant chemical structures identified by mass spectrometry were GlcN(C16:2)-GlcNAc-GlcNH2-GlcNAc(OH)(S), GlcN(C16,2)-GlcNAc-GlcNH2-GlcNH2(OH)(S), and GlcN(C16:2)-GlcNH2-GlcNH2-GlcNH2(OH)(S). In contrast to NodSm-IV(C16:2,S), the purified N-deacetylated derivatives were stable in the rhizosphere of Medicago sativa, indicating that the N-acetyl groups make the carbohydrate moiety of Nod factors accessible for glycosyl hydrolases of the host plant. The N-deacetylated derivatives displayed only a low level of activity in inducing root hair deformation. Furthermore, the N-deacetylated molecules were not able to stimulate Nod factor degradation by M. sativa roots, a response elicited by active Nod factors. These data show that N-acetyl groups of Nod factors are required for biological activity.

Elevation of the cytosolic free [Ca2+] is indispensable for the transduction of the Nod factor signal in alfalfa

In root hairs of alfalfa (Medicago sativa), the requirement of Ca(2+) for Nod factor signaling has been investigated by means of ion-selective microelectrodes. Measured 50 to 100 microm behind the growing tip, 0.1 microM NodRm-IV(C16:2,S) increased the cytosolic free [Ca2+] by about 0.2 pCa, while the same concentration of chitotetraose, the nonactive glucosamine backbone, had no effect. We demonstrate that NodRm-IV(C16:2,S) still depolarized the plasma membrane at external Ca(2+) concentrations below cytosolic values if the free EGTA concentration remained low ( Collapse

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MESH Headings

• Calcium/antagonists & inhibitors
• Calcium/metabolism
• Calcium/pharmacology
• Calcium Signaling/drug effects
• Calcium-Transporting ATPases/antagonists & inhibitors
• Calcium-Transporting ATPases/metabolism
• Chelating Agents/pharmacology
• Cytosol/metabolism
• Dose-Response Relationship, Drug
• Egtazic Acid/pharmacology
• Hydrogen-Ion Concentration
• Hydroquinones/pharmacology
• Lipopolysaccharides/antagonists & inhibitors
• Lipopolysaccharides/pharmacology
• Medicago sativa/cytology
• Medicago sativa/drug effects
• Medicago sativa/metabolism
• Membrane Potentials/drug effects
• Microelectrodes
• Plant Roots/cytology
• Plant Roots/drug effects
• Plant Roots/metabolism
• Strontium/pharmacology

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Affiliation(s)

H H Felle Botanisches Institut I, Justus-Liebig-Universität, Senckenbergstrasse 17, D-35390 Giessen, Germany.
E Kondorosi
A Kondorosi
M Schultze

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Nod factors modulate the concentration of cytosolic free calcium differently in growing and non-growing root hairs of Medicago sativa L

Using Ca(2+)-selective microelectrodes, the concentration of free calcium ([Ca(2+)]) in the cytosol has been measured in root hair cells of Medicago sativa L. in the presence of nodulation (Nod) factors. Growing root hairs of M. sativa displayed a steep apical [Ca(2+)] gradient, i.e. 604-967 nM in the tip compared with 95-235 nM in the basal region. When tested within the first 5 to 10 µm of the tip, addition of NodRm-IV(C16:2,S) decreased the cytosolic [Ca(2+)], whereas an increase was observed when tested behind the tip. Overall, this led to a partial dissipation of the [Ca(2+)] gradient. The Ca(2+) response was specific: it was equally well observed in the presence of NodRm-IV(Ac,C16:2,S), reduced with NodRm-IV(C16:0,S), but not with chitotetraose, the nonactive glucosamine backbone. In contrast to growing root hairs, non-growing root hairs without a tip-to-base cytosolic [Ca(2+)] gradient responded to NodRm-IV(C16:2,S) with an increase in cytosolic [Ca(2+)] at the tip as well as at the root hair base. We suggest that the response to Nod factors depends on the stage of development of the root hairs, and that changes in cytosolic [Ca(2+)] may play different roles in Nod-factor signaling: changes of cytosolic [Ca(2+)] in the apical part of the root hair may be related to root hair deformation, while the increase in [Ca(2+)] behind the tip may be essential for the amplification of the Nod signal, for its propagation and transduction to trigger downstream events.

Regulation of symbiotic root nodule development

Symbiosis between rhizobia and leguminous plants leads to the formation of N2-fixing root nodules. The interaction of rhizobia and plants shows a high degree of host specificity based on the exchange of chemical signals between the symbiotic partners. The plant signals, flavonoids exuded by the roots, activate the expression of nodulation genes, resulting in the production of the rhizobial lipochitooligosaccharide signals (Nod factors). Nod factors act as morphogens that, under conditions of nitrogen limitation, induce cells within the root cortex to divide and to develop into nodule primordia. This review focuses on how the production of Nod factors is regulated, how these signals are perceived and transduced by the plant root, and the physiological conditions and plant factors that control the early events leading to root nodule development.

Purification and characterization of a novel chitinase-lysozyme, of another chitinase, both hydrolysing Rhizobium meliloti Nod factors, and of a pathogenesis-related protein from Medicago sativa roots

The symbiosis between Rhizobium meliloti and Medicago sativa (Leguminosae) involves the interaction of lipochito-oligosaccharides (Nod factors) excreted by bacteria with specific proteins of the host plant. The cleavage of Nod factors can be used as an enzymic assay to identify novel hydrolytic enzymes. Here a soluble extract of 3-day-old roots was fractionated by anion exchange, affinity chromatography, gel filtration and native electrophoresis. Two acidic chitinases (pI 4.6-5.4), CHIT24 and CHIT36, designated in accordance with their molecular mass in kDa, were separated. CHIT24 cleaves all tested Nod factors to produce lipotrisaccharides with the preference NodRm-V(S)>NodRm-IV >NodRm-IV(S)>=NodRm-IV(Ac,S); it also hydrolyses colloidal 3H-chitin and has lysozyme activity. The kinetics of Nod factor degradation by CHIT24 depends on substrate structural parameters, namely the length of the oligosaccharide chain and sulphation (S) at the reducing end, but not much on acetylation (Ac) at the non-reducing end. The 25-residue N-terminal sequence of CHIT24 has no similarity with known chitinases or lysozymes, indicating that it is a novel type of hydrolase. CHIT36 also hydrolyses NodRm-V(S) into NodRm-III, but it is inactive towards NodRm-IV(S) and NodRm-IV(Ac,S) formed by R. meliloti. Finally, a 17 kDa protein, P17, was co-purified with CHIT24. It neither degrades Nod factors nor exhibits lysozyme activity and shows complete identity, at the 15-residue N-terminal sequence, with a class 10 pathogenesis-related protein, PR-10.

The role of lipochitooligosaccharides in root nodule organogenesis and plant cell growth

Lipochitooligosaccharides (Nod signals) excreted by rhizobia induce the formation of symbiotic root nodules in leguminous plants. This process is host plant specific, depending on the structural modifications of Nod signals. Rapid responses of plant roots in single cell assays have provided powerful tools in dissecting Nod signal transduction pathways and in elucidating the molecular basis of host specificity. Recent findings indicate that lipochitooligosaccharides, as well as symbiosis-related genes, also function in non legumes, pointing to a general role for these elements in plant morphogenesis.