Kneelike structure in the spectrum of the heavy component of cosmic rays observed with KASCADE-Grande

We report the observation of a steepening in the cosmic ray energy spectrum of heavy primary particles at about 8×10(16) eV. This structure is also seen in the all-particle energy spectrum, but is less significant. Whereas the "knee" of the cosmic ray spectrum at 3-5×10(15) eV was assigned to light primary masses by the KASCADE experiment, the new structure found by the KASCADE-Grande experiment is caused by heavy primaries. The result is obtained by independent measurements of the charged particle and muon components of the secondary particles of extensive air showers in the primary energy range of 10(16) to 10(18) eV. The data are analyzed on a single-event basis taking into account also the correlation of the two observables.

Dynamics and attenuation of acidic pharmaceuticals along a river stretch

While substantial knowledge on the occurrence of pharmaceuticals in the environment is available, their behavior and fate in surface waters is still poorly understood. Therefore, the aims of this study were to analyze the short-term dynamics of selected pharmaceuticals along a 13.6 km long river stretch downstream of a wastewater treatment plant (WWTP), and to quantify their attenuation by a mass balance approach. Four acidic pharmaceuticals (bezafibrate, clofibric acid, diclofenac, naproxen) with different attenuation properties were measured over a period of three weeks at high temporal resolution, and in situ photolysis experiments were carried out. The average concentrations of pharmaceuticals were between 9 +/- 4 and 339 +/- 133 ng L(-1), corresponding to loads between 1.9 +/- 1.2 and 63 +/- 37 g d(-1) (n = 134). The temporal dynamics of pharmaceuticals was closely related to discharge of the WWTP and precipitation, and highest concentrations were observed at the beginning of a discharge event. During a dry period, naproxen was eliminated along the river stretch with a dissipation time (DT(50)) of 3.6 +/- 2.1 days while the other compounds did not exhibit significant attenuation. As photolysis and other abiotic processes were of limited quantitative relevance, the attenuation of naproxen can most likely be attributed to biotransformation.

Pharmacological properties of purinergic receptors and their effects on proliferation and induction of neuronal differentiation of P19 embryonal carcinoma cells

We have used P19 embryonal carcinoma cells as in vitro model for early neurogenesis to study ionotropic P2X and metabotropic P2Y receptor-induced Ca(2+) transients and their participation in induction of proliferation and differentiation. In embryonic P19 cells, P2Y(1), P2Y(2) and P2X(4) receptors or P2X-heteromultimers with similar P2X(4) pharmacology were responsible for ATP and ATP analogue-induced Ca(2+) transients. In neuronal-differentiated cells, P2Y(2,) P2Y(6), P2X(2) and possibly P2X(2)/P2X(6) heteromeric receptors were the major mediators of the elevations in intracellular free calcium concentration [Ca(2+)](i). We have collected evidence for the involvement of metabotropic purinergic receptors in proliferation induction of undifferentiated and neural progenitor cells by using a BrdU-incorporation assay. ATP-, UTP-, ADP-, 2-MeS-ATP- and ADP-betaS-induced proliferation in P19 cells was mediated by P2Y(1) and P2Y(2) receptors as judged from pharmacological profiles of receptor responses. ATP-provoked acceleration of neuronal differentiation, determined by analysis of nestin and neuron-specific enolase gene and protein expression, also resulted from P2Y(1) and P2Y(2) receptor activation. Proliferation- and differentiation-induction involved the activation of inositol-trisphosphate sensitive intracellular Ca(2+) stores.

Mode of cembranoid action on embryonic muscle acetylcholine receptor

The mechanism of eupalmerin acetate (EUAC) actions on the embryonic muscle nicotinic acetylcholine receptor (nAChR) in BC3H-1 cells was studied by using whole-cell and single-channel patch-clamp current measurements. With whole-cell currents, EUAC did not act as an agonist on this receptor. Coapplication of 30 microM EUAC with 50 microM, 100 microM, or 500 microM carbamoylcholine (CCh) reversibly inhibited the current amplitude, whereas, with 20 microM CCh, current was increased above control values in the presence of EUAC. EUAC concentration curves (0.01-40 microM) obtained with 100 microM and 500 microM CCh displayed slope coefficients, n(H), significantly smaller than one, suggesting that EUAC bound to several sites with widely differing affinities on the receptor molecule. The apparent rate of receptor desensitization in the presence of EUAC and CCh was either slower than or equal to that obtained with CCh alone. The major finding from single-channel studies was that EUAC did not affect single-channel conductance or the ability of CCh to interact with the receptor. Instead, EUAC acted by increasing the channel closing rate constant. The results are not consistent with the competitive model for EUAC inhibition, with the sequential open-channel block model, or with inhibition by increased desensitization. The data are best accounted for by a model in which EUAC acts by closed-channel block at low concentrations, by positive modulation at intermediate concentrations, and by negative allosteric modulation of the open channel at high concentrations.

Delivery systems for in vivo use of nucleic Acid drugs

The notorious biotechnological advance of the last few decades has allowed the development of experimental methods for understanding molecular mechanisms of genes and new therapeutic approaches. Gene therapy is maturing into a viable, practical method with the potential to cure a variety of human illnesses. Some nucleic-acid-based drugs are now available for controlling the progression of genetic diseases by inhibiting gene expression or the activity of their gene products. New therapeutic strategies employ a wide range of molecular tools such as bacterial plasmids containing transgenic inserts, RNA interference and aptamers. A nucleic-acid based constitution confers a lower immunogenic potential and as result of the high stringency selection of large molecular variety, these drugs have high affinity and selectivity for their targets. However, nucleic acids have poor biostability thus requiring chemical modifications and delivery systems to maintain their activity and ease their cellular internalization. This review discusses some of the mechanisms of action and the application of therapies based on nucleic acids such as aptamers and RNA interference as well as platforms for cellular uptake and intracellular delivery of therapeutic oligonucleotides and their trade-offs.

Biodegradable magnesium scaffolds: Part II: peri-implant bone remodeling

In this study, histomorphometrical parameters of the peri-implant bone remodeling around degrading open-porous scaffolds made of magnesium alloy AZ91D were investigated and compared with the peri-implant bone remodeling around an autologous bone transplant in the contralateral side in a rabbit model after 3 and 6 months. Osteoblast activity was displayed by collagen I (alpha 2) mRNA in situ hybridization. Major scaffold degradation was completed within 3 months after implantation showing no osteolysis around the scaffolds, both after 3 and 6 months. Enhanced formation of unmineralized extracellular matrix and an enhanced mineral apposition rate adjacent to the degrading magnesium scaffolds were accompanied by an increased osteoclastic bone surface, which resulted in higher bone mass and a tendency to a more mature trabecular bone structure around the magnesium scaffolds compared to the control. These results show that even fast-degrading magnesium scaffolds induce extended peri-implant bone remodeling with a good biocompatibility. In summary, this study shows that degrading magnesium scaffolds promote both bone formation and resorption in a rabbit model and are therefore very promising candidates for the development of novel implants in musculoskeletal surgery.

Biodegradable magnesium scaffolds: Part 1: appropriate inflammatory response

Current tissue engineering strategies focus on the replacement of pathologically altered tissues by the transplantation of cells in combination with supportive biocompatible scaffolds. Scaffolds for tissue engineering strategies in musculoskeletal research require an appropriate mechanical stability. In recent studies, considerable attention has thus been given to magnesium alloys as biodegradable implants. The aim of this study was to characterize the biocompatibility of magnesium scaffolds by the inflammatory host response. Open porous scaffolds made of the magnesium alloy AZ91D were implanted into the distal femur condyle of rabbits and were compared to autologous bone, which was transplanted into the contralateral condyle in a 3 and 6 months follow-up group. After 3 months, magnesium scaffolds were already largely degraded and most of the original magnesium alloy has disappeared. Concomitantly, a fibrous capsule enclosed the operation site. Histological analysis revealed that the magnesium scaffolds caused no significant harm to their neighboring tissues. This study shows that even fast degrading magnesium scaffolds show a good biocompatibility and react in vivo with an appropriate inflammatory host response. Magnesium alloy based implants are therefore a very promising approach in the development of mechanically suitable and open porous scaffolds for the replacement of subchondral bone in cartilage tissue engineering.

P19 embryonal carcinoma cells as in vitro model for studying purinergic receptor expression and modulation of N-methyl-d-aspartate–glutamate and acetylcholine receptors during neuronal differentiation

The in vitro differentiation of P19 murine embryonal carcinoma cells to neurons resembles developmental stages which are encountered during neuronal development. Three days following induction to neuronal differentiation by retinoic acid, most cells of the P19 population lost expression of the stage specific embryonic antigen (SSEA-1) and expressed the neural progenitor cell specific antigen nestin. Beginning from day 4 of differentiation nestin expression was down-regulated, and expression of neuron-specific enolase as marker of differentiated neurons increased. The molecular mechanisms underlying neuronal differentiation are poorly understood. We have characterized the participation of purinergic ionotropic (P2X) and metabotropic (P2Y) receptors at mRNA transcription and protein levels as well as ATP-induced Ca2+ transients during neuronal differentiation of P19 cells. Gene and protein expression of P2X2, P2X6, P2Y2, and P2Y6 receptors increased during the course of differentiation, whereas P2X3, P2X4, P2Y1 and P2Y4 receptor expression was high in embryonic P19 cells and then decreased following induction of P19 cells to differentiation. P2X1 receptor protein expression was only detected on days 2 and 4 of differentiation. Although P2X5 and P2X7 mRNA transcription was present, no protein expression for this receptor subunit could be detected throughout the differentiation process. In undifferentiated cells, mainly ionotropic P2X receptors contributed to the ATP-induced Ca2+-response. In neuronal-differentiated P19 cells, the ATP-induced Ca2+-response was increased and the metabotropic component predominated. Purinergic receptor function is implicated to participate in neuronal maturation, as cholinergic and glutamate-N-methyl-D-aspartate (NMDA) induced calcium responses were affected when cells were differentiated in the presence of purinergic receptor antagonists pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (PPADS), suramin or reactive blue-2. Our data suggest that inhibition of P2Y1 and possibly P2X2 receptors led to a loss of NMDA receptor activity whereas blockade of possibly P2X2 and P2Y2 purinergic receptors during neuronal differentiation of P19 mouse led to inhibition of cholinergic receptor responses.

Neurotransmitter receptor expression and activity during neuronal differentiation of embryonal carcinoma and stem cells: from basic research towards clinical applications

Embryonal carcinoma and embryonic stem cells have served as models to understand basic aspects of neuronal differentiation and are promising candidates for regenerative medicine. Besides being well characterized regarding the capability of embryonal carcinoma and embryonic stem cells to be precursors of different tissues, the molecular mechanisms controlling neuronal differentiation are hardly understood. Neuropeptide and neurotransmitter receptors are expressed at early stages of differentiation prior to synaptogenesis, triggering transient changes in calcium concentration and inducing neurone-specific gene expression. In vitro neuronal differentiation of embryonal carcinoma and embryonic stem cells closely resembles early neuronal development in vivo. Murine P19 EC cells are a well-characterized model for in vitro differentiation, which upon treatment with retinoic acid differentiate into neurones. Expression and activity of various receptor proteins is regulated during their differentiation. Stimulation of kinin-B2, endothelin-B, muscarinic acetylcholine, and N-methyl-D-aspartate receptors results in transient increases of intracellular free calcium concentration [Ca(2+)](i) in P19 cells undergoing neuronal differentiation, whereas embryonal cells do not respond or show a smaller change in [Ca(2+)](i) than differentiating cells. Receptor inhibition, as studied with the example of the kinin-B2 receptor, aborts neuronal maturation of P19 cells, demonstrating the crucial importance of B2 receptors during the differentiation process. Future success in obtaining desired neuronal phenotypes from pluripotent cells in vitro may offer new therapeutic perspectives for curing genetic and acquired dysfunctions of the developing and adult nervous system.

Optimal parameters for the treatment of leg veins using Nd:YAG lasers at 1064 nm

BACKGROUND

The treatment of large vessels such as leg veins is successfully performed in clinical practice using pulsed Nd:YAG lasers. However, it is still unclear how laser parameters such as wavelength, fluence and pulse duration influence vessel destruction in leg veins.

OBJECTIVES

To elucidate the governing parameters in selective photothermolysis of large vessels.

METHODS

A recently developed mathematical model for photothermolysis has been adapted for the treatment of leg veins. The model was used to analyse the effectiveness of the selective photothermolysis process in laser treatment of leg veins by Nd:YAG at 1064 nm. The efficiency of laser-induced vessel heating was defined as a ratio between the absorbed and delivered energy.

RESULTS

The efficiency improved with increasing vessel diameter, in agreement with clinical findings in various studies. The pulse duration made a minor contribution for laser fluences of 100-400 J cm(-2), whereas the efficiency was better for a small spot. The use of moderate fluences of 100-200 J cm(-2) reduced excess dermis heating and pain.

CONCLUSIONS

We provide reference parameters for optimal treatment of leg veins using Nd:YAG lasers at 1064 nm. Our model predicts a maximal efficiency of a range of fluences (100-200 J cm(-2)) and pulse durations (10-100 ms).

RNA aptamers: from basic science towards therapy

The SELEX technique (systematic evolution of ligands by exponential enrichment) provides a powerful tool for the in vitro selection of nucleic acid ligands (aptamers) from combinatorial oligonucleotide libraries against a target molecule. In the beginning of the technique's use, RNA molecules were identified that bind to proteins that naturally interact with nucleic acids or to small organic molecules. In the following years, the use of the SELEX technique was extended to isolate oligonucleotide ligands (aptamers) for a wide range of proteins of importance for therapy and diagnostics, such as growth factors and cell surface antigens. These oligonucleotides bind their targets with similar affinities and specificities as antibodies do. The in vitro selection of oligonucleotides with enzymatic activity, denominated aptazymes, allows the direct transduction of molecular recognition to catalysis. Recently, the use of in vitro selection methods to isolate protein inhibitors has been extended to complex targets, such as membrane-bound receptors, and even entire cells. RNA aptamers have also been expressed in living cells. These aptamers, also called intramers, can be used to dissect intracellular signal transduction pathways. The utility of RNA aptamers for in vivo experiments, as well as for diagnostic and therapeutic purposes, is considerably enhanced by chemical modifications, such as substitutions of the 2'-OH groups of the ribose backbone in order to provide resistance against enzymatic degradation in biological fluids. In an alternative approach, Spiegelmers are identified through in vitro selection of an unmodified D-RNA molecule against a mirror-image (i.e. a D-peptide) of a selection target, followed by synthesis of the unnatural nuclease-resistant L-configuration of the RNA aptamer that recognizes the natural configuration of its selection target (i.e. a L-peptide). Recently, nuclease-resistant inhibitory RNA aptamers have been developed against a great variety of targets implicated in disease. Some results have already been obtained in animal models and in clinical trials.

Quantification of cell-cycle distribution and mitotic index in Hydra by flow cytometry

The applicability of flow cytometry (FCM) to analyse cell-cycle distribution and mitotic cells in Hydra oligactis and Hydra vulgaris is demonstrated. The freshwater polyps H. vulgaris and H. oligactis are well-accepted animal models for studying cell proliferation, regeneration and differentiation. Disintegrated animals were labelled for FCM analysis according to the method of Nuesse et al. [(1990) Flow cytometric analysis of G(1) and G(2)/M-phase subpopulations in mammalian cell nuclei using side scatter and DNA content measurements. Cytometry 11, 813]. Proliferation and regeneration experiments, in the absence or presence of the oligopeptide head activator, were quantified. Cell-cycle analysis of different parts of the animals shows low proliferation in the head region and high proliferation in the gastric and foot regions. Cell-cycle analysis of different parts of Hydra, comparison of H. oligactis and H. vulgaris, as well as pharmacological treatment, yielded results that are in agreement with prior microscopic analysis. Our results demonstrate that FCM is an appropriate technique for quantifying proliferation in this animal model. It can be used for basic research on development, regeneration and differentiation as well as for innovative drug investigation and toxicology studies.

Detection and imaging of atmospheric radio flashes from cosmic ray air showers

The nature of ultrahigh-energy cosmic rays (UHECRs) at energies >10(20) eV remains a mystery. They are likely to be of extragalactic origin, but should be absorbed within approximately 50 Mpc through interactions with the cosmic microwave background. As there are no sufficiently powerful accelerators within this distance from the Galaxy, explanations for UHECRs range from unusual astrophysical sources to exotic string physics. Also unclear is whether UHECRs consist of protons, heavy nuclei, neutrinos or gamma-rays. To resolve these questions, larger detectors with higher duty cycles and which combine multiple detection techniques are needed. Radio emission from UHECRs, on the other hand, is unaffected by attenuation, has a high duty cycle, gives calorimetric measurements and provides high directional accuracy. Here we report the detection of radio flashes from cosmic-ray air showers using low-cost digital radio receivers. We show that the radiation can be understood in terms of the geosynchrotron effect. Our results show that it should be possible to determine the nature and composition of UHECRs with combined radio and particle detectors, and to detect the ultrahigh-energy neutrinos expected from flavour mixing.

Selection of 2?-Fluoro-modified RNA Aptamers for Alleviation of Cocaine and MK-801Inhibition of the Nicotinic Acetylcholine Receptor

The nicotinic acetylcholine receptor (nAChR) belongs to a group of five structurally related proteins that regulate signal transmission between approximately 10(12) cells of the mammalian nervous system. Many therapeutic agents and abused drugs inhibit the nAChR, including the anti-convulsant MK-801 and the abused drug cocaine. Many attempts have been made to find compounds that prevent inhibition by cocaine. Use of transient kinetic techniques to investigate the inhibition of the receptor by MK-801 and cocaine led to an inhibition mechanism not previously proposed. The mechanism led to the development of combinatorially synthesized RNA ligands that alleviate inhibition of the receptor. However, these ligands are relatively unstable. Here we determined whether much more stable 2'-fluoro-modified RNA ligands can be prepared and used to study the alleviation of receptor inhibition. Two classes of 2'-fluoro-modified RNA ligands were obtained: One class binds with higher affinity to the cocaine-binding site on the closed-channel form and, as predicted by the mechanism, inhibits the receptor. The second class binds with equal or higher affinity to the cocaine-binding site on the open-channel form and, as predicted by the mechanism, does not inhibit the receptor, and does alleviate cocaine and MK-801 inhibition of the nAChR. The stability of these 2'-fluoro-RNAs expands the utility of these ligands.

[Dialysis associated skin changes]

Patients with end-stage renal disease often suffer from different dermatologic conditions. Reports indicate that 50-100% of patients with end-stage renal disease have at least one cutaneous disorder. The persisting chronic uremia is responsible for a variety of structural and functional skin changes. Dialysis or even renal transplantation leads to an improvement of some uremia associated skin disorders, others however can persist.

Role of Laser Therapy in Dermatology – Clinical Aspects

BACKGROUND

Laser therapy has become an integral part of therapeutic alternatives in dermatology. Nevertheless, there are only few statistical data on the role of lasers in everyday practice of dermatological clinics.

OBJECTIVE

Analysis of laser patients, indications and lasers used.

METHODS

We analysed 10244 patients treated with laser therapy in the Department of Dermatology at the University of Regensburg from 1992 to 2000. This figure represents 9.6 % of all patients seen during that period.

RESULTS

Vascular lesions (hemangiomas, port-wine stains, telangiectasias) represented the most common indication (more than 70%) followed by infectious disorders (mostly papillomavirus lesions) as well as the removal of hairs and tattoos. Accordingly, the most frequently used laser was the flashlamp-pumped pulsed dye laser (585 nm) followed by the argon ion, the long-pulse tunable flashlamp-pumped pulsed dye laser, the Q-switch ruby laser, and the CO(2)-laser. In recent years, the percentage of indications and lasers used has changed significantly, reflecting the development of new lasers and the introduction of new indications.

CONCLUSIONS

The results confirm the important role of laser therapy in dermatology.

The use of inferior vena cava filter as a treatment modality for massive pulmonary embolism. A case series and review of pathophysiology

The use of inferior vena cava (IVC) filter for massive pulmonary emboli (PE) with cardiopulmonary instability has not been clinically studied. We present a case series of six such patients who received an IVC filter with anticoagulation rather than thrombolysis because of high risk of bleeding. Acute pulmonary embolectomy was considered, but was not possible for a variety of individual clinical situations. These six hospitalized patients prospectively followed during their admission. They were triaged to three medical intensive care units (ICUs) and one surgical ICU in three university teaching hospitals. One patient was transferred from another institution. All six patients had severe hypoxia and tenuous cardiopulmonary status. All required high inspiratory oxygen and hemodynamic support; two required mechanical ventilation and vasopressors. An IVC filter was placed emergently and anticoagulation was started immediately All six patients had resolution of pulmonary thromboemboli (PTE) on anticoagulation while the IVC filter prevented further PE. All six patients were discharged home in their pre-critical illness state. None ofthe patients suffered complications from this therapy and had excellent resolution ofcardiopulmonary collapse. The IVC filter placement prevented further major embolic events while the PTE resolved with anticoagulation. An IVC filter should be considered as an adjunct to anticoagulation therapy for those patients with massive PE and cardiopulmonary instability who are not candidates for thrombolysis, and acute pulmonary embolectomy is not readily available or is of very high risk.