Structure of the native myosin filament in the relaxed cardiac sarcomere

The thick filament is a key component of sarcomeres, the basic units of striated muscle1. Alterations in thick filament proteins are associated with familial hypertrophic cardiomyopathy and other heart and muscle diseases2. Despite the central importance of the thick filament, its molecular organization remains unclear. Here we present the molecular architecture of native cardiac sarcomeres in the relaxed state, determined by cryo-electron tomography. Our reconstruction of the thick filament reveals the three-dimensional organization of myosin, titin and myosin-binding protein C (MyBP-C). The arrangement of myosin molecules is dependent on their position along the filament, suggesting specialized capacities in terms of strain susceptibility and force generation. Three pairs of titin-α and titin-β chains run axially along the filament, intertwining with myosin tails and probably orchestrating the length-dependent activation of the sarcomere. Notably, whereas the three titin-α chains run along the entire length of the thick filament, titin-β chains do not. The structure also demonstrates that MyBP-C bridges thin and thick filaments, with its carboxy-terminal region binding to the myosin tails and directly stabilizing the OFF state of the myosin heads in an unforeseen manner. These results provide a foundation for future research investigating muscle disorders involving sarcomeric components.

A cryogenic, coincident fluorescence, electron, and ion beam microscope

Cryogenic electron tomography (cryo-ET) combined with subtomogram averaging, allows in situ visualization and structure determination of macromolecular complexes at subnanometre resolution. Cryogenic focused ion beam (cryo-FIB) micromachining is used to prepare a thin lamella-shaped sample out of a frozen-hydrated cell for cryo-ET imaging, but standard cryo-FIB fabrication is blind to the precise location of the structure or proteins of interest. Fluorescence-guided focused ion beam (FIB) milling at target locations requires multiple sample transfers prone to contamination, and relocation and registration accuracy is often insufficient for 3D targeting. Here, we present in situ fluorescence microscopy-guided FIB fabrication of a frozen-hydrated lamella to address this problem: we built a coincident three-beam cryogenic correlative microscope by retrofitting a compact cryogenic microcooler, custom positioning stage, and an inverted widefield fluorescence microscope (FM) on an existing FIB scanning electron microscope. We show FM controlled targeting at every milling step in the lamella fabrication process, validated with transmission electron microscope tomogram reconstructions of the target regions. The ability to check the lamella during and after the milling process results in a higher success rate in the fabrication process and will increase the throughput of fabrication for lamellae suitable for high-resolution imaging.

Can one determine the density of an individual synthetic macromolecule?

Dendronized polymers (DPs) are large and compact main-chain linear polymers with a cylindrical shape and cross-sectional diameters of up to ∼15 nm. They are therefore considered molecular objects, and it was of interest whether given their experimentally accessible, well-defined dimensions, the density of individual DPs could be determined. We present measurements on individual, deposited DP chains, providing molecular dimensions from scanning and transmission electron microscopy and mass-per-length values from quantitative scanning transmission electron microscopy. These results are compared with density values obtained from small-angle X-ray scattering on annealed bulk specimen and with classical envelope density measurements, obtained using hydrostatic weighing or a density gradient column. The samples investigated comprise a series of DPs with side groups of dendritic generations g = 1-8. The key findings are a very large spread of the density values over all samples and methods, and a consistent increase of densities with g over all methods. While this work highlights the advantages and limitations of the applied methods, it does not provide a conclusive answer to the question of which method(s) to use for the determination of densities of individual molecular objects. We are nevertheless confident that these first attempts to answer this challenging question will stimulate more research into this important aspect of polymer and soft matter science.

SPHIRE-crYOLO is a fast and accurate fully automated particle picker for cryo-EM

Selecting particles from digital micrographs is an essential step in single-particle electron cryomicroscopy (cryo-EM). As manual selection of complete datasets-typically comprising thousands of particles-is a tedious and time-consuming process, numerous automatic particle pickers have been developed. However, non-ideal datasets pose a challenge to particle picking. Here we present the particle picking software crYOLO which is based on the deep-learning object detection system You Only Look Once (YOLO). After training the network with 200-2500 particles per dataset it automatically recognizes particles with high recall and precision while reaching a speed of up to five micrographs per second. Further, we present a general crYOLO network able to pick from previously unseen datasets, allowing for completely automated on-the-fly cryo-EM data preprocessing during data acquisition. crYOLO is available as a standalone program under http://sphire.mpg.de/ and is distributed as part of the image processing workflow in SPHIRE.

Schmerztherapie mit Metamizol

Gegenstand und Ziel: Die vorliegende Arbeit soll den derzeitigen Wissensstand über die pharmakologische und klinische Wirkung von Metamizol bei Hund, Katze Maus und Ratte vorstellen. Metamizol erlebt in den letzten Jahren eine Renaissance, vor allem in der Humanmedizin. Lange Zeit wurde Metamizol als schwaches Analgetikum mit vorwiegend antipyretischer Wirkung eingestuft und die pharmakologische Wirkung war lange Zeit unbekannt. Heute ist wissenschaftlich nachgewiesen, dass zentrale und periphere Wirkmechanismen für die potente analgetische Wirkung von Metamizol verantwortlich sind. Opioiderge Mechanismen und Hemmung der Zyklooxygenasen gelten heute als gesicherte Wirkmechanismen von Metamizol. Metamizol wirkt aber auch antipyretisch, gering antiphlogistisch, spasmolytisch und antikonvulsiv. Die analgetische Wirkung ist mit der von Opioiden vergleichbar. Die hypotensive Nebenwirkung bei intravenöser Injektion lässt sich durch langsame Applikation weitestgehend vermeiden. Eine Agranulozytose wurde bisher in der Veterinärmedizin nicht beobachtet und auch in der Humanmedizin liegt die Inzidenz unter 0,008%. Die Magen-Darm-Trakt-Verträglichkeit von Metamizol ist als gut einzustufen. Schlussfolgerung und klinische Relevanz: Der vorliegende Artikel zeigt, dass Metamizol auch in der Veterinärmedizin potent analgetisch wirkt und die Verträglichkeit als sehr gut zu bewerten ist.

Multiple roles of filopodial dynamics in particle capture and phagocytosis and phenotypes of Cdc42 and Myo10 deletion

Macrophage filopodia, finger-like membrane protrusions, were first implicated in phagocytosis more than 100 years ago, but little is still known about the involvement of these actin-dependent structures in particle clearance. Using spinning disk confocal microscopy to image filopodial dynamics in mouse resident Lifeact-EGFP macrophages, we show that filopodia, or filopodia-like structures, support pathogen clearance by multiple means. Filopodia supported the phagocytic uptake of bacterial (Escherichia coli) particles by (i) capturing along the filopodial shaft and surfing toward the cell body, the most common mode of capture; (ii) capturing via the tip followed by retraction; (iii) combinations of surfing and retraction; or (iv) sweeping actions. In addition, filopodia supported the uptake of zymosan (Saccharomyces cerevisiae) particles by (i) providing fixation, (ii) capturing at the tip and filopodia-guided actin anterograde flow with phagocytic cup formation, and (iii) the rapid growth of new protrusions. To explore the role of filopodia-inducing Cdc42, we generated myeloid-restricted Cdc42 knock-out mice. Cdc42-deficient macrophages exhibited rapid phagocytic cup kinetics, but reduced particle clearance, which could be explained by the marked rounded-up morphology of these cells. Macrophages lacking Myo10, thought to act downstream of Cdc42, had normal morphology, motility, and phagocytic cup formation, but displayed markedly reduced filopodia formation. In conclusion, live-cell imaging revealed multiple mechanisms involving macrophage filopodia in particle capture and engulfment. Cdc42 is not critical for filopodia or phagocytic cup formation, but plays a key role in driving macrophage lamellipodial spreading.

A Versatile High-Vacuum Cryo-transfer System for Cryo-microscopy and Analytics

Cryogenic microscopy methods have gained increasing popularity, as they offer an unaltered view on the architecture of biological specimens. As a prerequisite, samples must be handled under cryogenic conditions below their recrystallization temperature, and contamination during sample transfer and handling must be prevented. We present a high-vacuum cryo-transfer system that streamlines the entire handling of frozen-hydrated samples from the vitrification process to low temperature imaging for scanning transmission electron microscopy and transmission electron microscopy. A template for cryo-electron microscopy and multimodal cryo-imaging approaches with numerous sample transfer steps is presented.

Facile synthesis of a peptidic Au(I)-metalloamphiphile and its self-assembly into luminescent micelles in water

We report a short synthetic route for the preparation of a peptidic Au(I)-metalloamphiphile which, in buffered environments of physiological ionic strength, self-assembles into luminescent micellar nanostructures of 14 nm in diameter.

Der p 11 is a major allergen for house dust mite-allergic patients suffering from atopic dermatitis

House dust mites (HDMs) belong to the most potent indoor allergen sources worldwide and are associated with allergic manifestations in the respiratory tract and the skin. Here we studied the importance of the high-molecular-weight group 11 allergen from Dermatophagoides pteronyssinus (Der p 11) in HDM allergy. Sequence analysis showed that Der p 11 has high homology to paramyosins from mites, ticks, and other invertebrates. A synthetic gene coding for Der p 11 was expressed in Escherichia coli and rDer p 11 purified to homogeneity as folded, alpha-helical protein as determined by circular dichroism spectroscopy. Using antibodies raised against rDer p 11 and immunogold electron microscopy, the allergen was localized in the muscle beneath the skin of mite bodies but not in feces. IgE reactivity of rDer p 11 was tested with sera from HDM-allergic patients from Europe and Africa in radioallergosorbent test-based dot-blot assays. Interestingly, we found that Der p 11 is a major allergen for patients suffering from atopic dermatitis (AD), whereas it is only a minor allergen for patients suffering from respiratory forms of HDM allergy. Thus, rDer p 11 might be a useful serological marker allergen for the identification of a subgroup of HDM-allergic patients suffering from HDM-associated AD.

Tuning the pH-triggered self-assembly of dendritic peptide amphiphiles using fluorinated side chains

We report the synthesis of a series of anionic dendritic peptide amphiphiles of increasing hydrophobic character and describe their self-assembly into supramolecular nanorods using pH and ionic strength dependent state diagrams.

[Diagnostic value of CT and MRI for the diagnosis of coronoid pathology in the dog]

OBJECTIVE

The diagnostic value of CT and MRI regarding the diagnosis of coronoid pathology in the dog.

MATERIAL AND METHODS

Computed tomography (CT) and magnetic resonance imaging (MRI) of the elbow joint were performed in dogs with clinical and radiological signs of coronoid pathology. Afterwards, all dogs underwent arthroscopic surgery. For the computed tomographic examination, a 16-slice-CT-scanner spiral-CT (Philips Brilliance 16) was used. The MRI-examination was performed with a 1-Tesla superconducting magnet (Phillips Intera 1.0). T1 and T2 weighted images with different sequences were acquired.

RESULTS

In total, 44 elbow joints from 44 patients (total of 12 breeds, including mixed breeds) were examined. The most represented breeds were Labrador Retrievers (38.6%, n=17), mixed breed dogs (22.7%, n=10) and Golden Retrievers (11.4%, n=5) were represented most. The age of the 30 male dogs (68%) and 14 female dogs (32%) ranged from 6 to 117 months (mean 2.25 years). Using CT, the following results could be evaluated: a) fissure at the level of the Processus coronoideus medialis ulnae (PCM) in 66% (n=29); b) fragments at the level of the PCM in 55% (n=24); c) deformation at the level of the PCM in all 44 joints; d) increased opacity at the level of the base of the PCM in all 44 joints; e) heterogenous opacity at the apex of the PCM in 91% (n=41). With MRI, the following results could be evaluated: a) fissure at the level of the PCM in 59% (n=26); b) fragments at the level of the PCM in 57% (n=25); c) deformation at the level of the PCM in 86% (n=38); d) increased opacity at the level of the base of the PCM, thus making assessment impossible; e) heterogenous opacity at the apex of the PCM, thus making assessment impossible.

CONCLUSION AND CLINICAL RELEVANCE

Both diganostic imaging modalities are appropriate for evaluating coronoid pathology in the dog.

Systematic review of the management of canine osteoarthritis

This review assesses the evidence for the efficacy of therapies used in the management of osteoarthritis in dogs on the basis of papers published in peer-reviewed journals in English between 1985 and July 2007. Sixty-eight papers were identified and evaluated. They considered four alternative therapies, one use of functional food, two intra-articular agents, six nutraceutical agents, 21 pharmacological agents, two physical therapies, three surgical techniques and two combinations of weight control. There was a high level of comfort (strong evidence) for the efficacy of carprofen, firocoxib and meloxicam, and a moderate level of comfort for the efficacy of etodolac in modifying the signs of osteoarthritis. There was a moderate level of comfort for the efficacy of glycosaminoglycan polysulphate, licofelone, elk velvet antler and a functional food containing green-lipped mussel for the modification of the structures involved in the disease. There was weak or no evidence in support of the use of doxycycline, electrostimulated acupuncture, extracorporeal shockwave therapy, gold wire acupuncture, hyaluronan, pentosan polysulphate, P54FP (extract of turmeric), tiaprofenic acid or tibial plateau levelling osteotomy.

No evidence for productive PERV infection of baboon cells in in vivo infection model

OBJECTIVES

The discovery that pig endogenous retroviruses are infectious for human cells in vitro lead to vehement discussions about the possible risk of infection after clinical xenotransplantation. Since PERV transmission to non-human primate cells in vitro has been observed, similar to human cells, infection studies in non-human primates should represent the best model to analyze a potential PERV transmission after xenotransplantation. However, it is still open to discussion, whether non-human primate cells can be infected productively-similar to human cells- and whether those species are suitable to analyze PERV infection risks in vivo.

METHODS

In vitro, only few cell types can be tested for susceptibility. We developed a pig to baboon cell transplantation model with special emphasis on B-cell effective immunosuppression, removal of anti Gal-alpha 1,3-Gal-antibodies, inhibition of the complement cascade and long term survival of transplanted cellular grafts. This model allows us to investigate in vivo, whether any baboon cell types may be permissive for productive PERV infection. The xenograft recipients were investigated for up to 535 days post transplantation. Gal-alpha 1,3-Gal-antibody and complement levels were monitored. Potential PERV transmission was analyzed, not only in PBMC, but in a variety of tissue samples as well as in serum and plasma samples by PCR, RT-PCR and by detection of RT-activity. Moreover, potential PERV specific immune responses were studied by a highly sensitive Western-Blot-assay.

RESULTS

Despite several days of extremely low levels of Gal-alpha 1,3-Gal-antibody and complement, and despite of long term xenochimerism, no evidence for PERV infection was obtained in any of the tested tissues or in the tested serum samples.

CONCLUSION

This study supplies further evidence for a low susceptibility of baboons towards productive PERV infection after xenotransplantation.

[Sevoflurane (SEVOrane) as an inhalation anesthetic in dogs in comparison with halothane and isoflurane]

1969 Sevofluran was synthesized and in December 1995 licensed for clinical use in Germany. The low blood/gas partition coefficient is responsible for the fast uptake and elimination of sevoflurane. Sevoflurane does not irritate the airway. In human medicine no side effect of liver- and kidney function have been seen after sevofluran anaesthesia. There is low cardiovascular and respiratory depression caused by sevoflurane. In this study the use of sevoflurane in dogs should be tested and compared with isoflurane and halothane anaesthesia. All dogs were premedicated with /-methadon and diazepam. No significant depression of the cardiovascular system was seen. Neither kidney-nor hepatotoxic side effects could be found after sevoflurane, isoflurane and halothane anaesthesia. After sevoflurane anaesthesia the dogs woke up quietly and without any excitation and were able to stand on average ten minutes earlier after sevoflurane anaesthesia than after isoflurane and 85 minutes earlier than after halothane anaesthesia.

[Excision arthroplasty of the hip joint in dogs and cats. Long-term results of the veterinary surgery clinic at the Justus Liebig University of Giessen]

Since the introduction of excision arthoplasty in veterinary medicine the question of indication is often asked. The maximum of the patient's body weight up to which surgery should be performed is another discussed problem. A long-term study from January 1985 to July 1995 at the Veterinary Surgery Department at the Justus-Liebig-University was carried out to answer these questions (222 patients, 155 dogs and 67 cats). Trauma and Legg-Calvé-Perthes disease came first in the list of indications. In case of postoperative problems trouble with lameness after high activity, long rest or at the time of change in weather could be seen. No owner of an animal thought that the life quality of his animal was restricted by this occasional problems. At a body weight over 30 kg the occasional problems were more often seen but every patient had less clinical problems after surgery than before. In this group no deterioration was seen.

[Total intravenous anesthesia (TIVA) with alphaxolon/alphadolon (Saffan) for permanent restraint of two cats with severe dyspnea]

Total intravenous anaesthesia is a form of anaesthesia which is more often used in human medicine for high risk patients. The case reports of two cats with a severe dyspnoe are presented. Both patients received anaesthesia with the steroid anaesthetic agent Saffan for 19 and 25 hours, respectively. Saffan is a well-tolerated agent with little side effects. Dosage and monitoring results are presented.

[Sterility--a woman's concern? Coping behavior and partnership structure of sterile couples of various diagnostic groups]

Three groups of sterile couples with functional, tubal and andrologically caused sterility were compared for the evaluation of sex- and diagnosis-dependent kinds of overcoming of their disease. Anamnestic data, anxiety, the coping strategy of sterility and as well the couple and personality structure are analysed. Independent of the organic cause of sterility the women showed a higher emotional reaction level (anxiety, coping stress) than their husbands. In all groups the "healthy" partners dominate. The subfertile men seem to be more subordinate, less engaged and interested and not so anxious as their wives and as the husbands of tubal sterile women. The healthy women with andrologically caused sterility present a highly emotional engagement in the overcoming and treatment of their disease. Possible emotional mechanisms and social stereotypes of self-presentation are discussed, which may cause the intense engagement of the women independent of the organic cause of sterility.