A primary microcephaly-associated sas-6 mutation perturbs centrosome duplication, dendrite morphogenesis, and ciliogenesis in Caenorhabditis elegans

The human SASS6(I62T) missense mutation has been linked with the incidence of primary microcephaly in a Pakistani family, although the mechanisms by which this mutation causes disease remain unclear. The SASS6(I62T) mutation corresponds to SAS-6(L69T) in Caenorhabditis elegans. Given that SAS-6 is highly conserved, we modeled this mutation in C. elegans and examined the sas-6(L69T) effect on centrosome duplication, ciliogenesis, and dendrite morphogenesis. Our studies revealed that all the above processes are perturbed by the sas-6(L69T) mutation. Specifically, C. elegans carrying the sas-6(L69T) mutation exhibit an increased failure of centrosome duplication in a sensitized genetic background. Further, worms carrying this mutation also display shortened phasmid cilia, an abnormal phasmid cilia morphology, shorter phasmid dendrites, and chemotaxis defects. Our data show that the centrosome duplication defects caused by this mutation are only uncovered in a sensitized genetic background, indicating that these defects are mild. However, the ciliogenesis and dendritic defects caused by this mutation are evident in an otherwise wild-type background, indicating that they are stronger defects. Thus, our studies shed light on the novel mechanisms by which the sas-6(L69T) mutation could contribute to the incidence of primary microcephaly in humans.

Ångstrom-Depth Resolution with Chemical Specificity at the Liquid-Vapor Interface

The determination of depth profiles across interfaces is of primary importance in many scientific and technological areas. Photoemission spectroscopy is in principle well suited for this purpose, yet a quantitative implementation for investigations of liquid-vapor interfaces is hindered by the lack of understanding of electron-scattering processes in liquids. Previous studies have shown, however, that core-level photoelectron angular distributions (PADs) are altered by depth-dependent elastic electron scattering and can, thus, reveal information on the depth distribution of species across the interface. Here, we explore this concept further and show that the experimental anisotropy parameter characterizing the PAD scales linearly with the average distance of atoms along the surface normal obtained by molecular dynamics simulations. This behavior can be accounted for in the low-collision-number regime. We also show that results for different atomic species can be compared on the same length scale. We demonstrate that atoms separated by about 1 Å along the surface normal can be clearly distinguished with this method, achieving excellent depth resolution.

[Surgical treatment of proximal femoral fractures in high-risk geriatric patients under peripheral regional anesthesia : A clinical case series]

The authors describe in a clinical case series (n = 7) of older (age 78-95 years) high-risk patients the successful surgical treatment of proximal femoral fractures in a peripheral regional anesthesia technique. After positioning on the non-fractured side, a double injection technique (dual guidance concept: sonography plus nerve stimulation) was chosen. The injections were performed parasacrally (blockade of the sacral plexus under the piriformis muscle) and lumbar-paravertebrally (psoas compartment block and transmuscular quadratus lumborum block). Per block 15 ml ropivacaine 0.5% or 20 ml ropivacaine 0.375% was administered. The total dose of 225 mg ropivacaine was never exceeded. In 5 out of 7 cases a supplemental medication with 2 times 5 μg sufentanil (n = 2) and/or 1-1.5 mg/kg body weight and h propofol (n = 4) was administered with spontaneous breathing. In addition to potential benefits, the authors also discuss limitations of the procedure, for example by the use of oral anticoagulants.

Single-Molecule Insight Into Target Recognition by CRISPR-Cas Complexes

Ribonucleoprotein (RNP) complexes from CRISPR-Cas systems have attracted enormous interest since they can be easily and flexibly reprogrammed to target any desired locus for genome engineering and gene regulation applications. Basis for the programmability is a short RNA (crRNA) inside these complexes that recognizes the target nucleic acid by base pairing. For CRISPR-Cas systems that target double-stranded DNA this results in local DNA unwinding and formation of a so-called R-loop structure. Here we provide an overview how this target recognition mechanism can be dissected in great detail at the level of a single molecule. Specifically, we demonstrate how magnetic tweezers are applied to measure the local DNA unwinding at the target in real time. To this end we introduce the technique and the measurement principle. By studying modifications of the consensus target sequence, we show how different sequence elements contribute to the target recognition mechanism. From these data, a unified target recognition mechanism can be concluded for the RNPs Cascade and Cas9 from types I and II CRISPR-Cas systems. R-loop formation is hereby initiated on the target at an upstream element, called protospacer adjacent motif (PAM), from which the R-loop structure zips directionally toward the PAM-distal end of the target. At mismatch positions, the R-loop propagation stalls and further propagation competes with collapse of the structure. Upon full R-loop zipping conformational changes within the RNPs trigger degradation of the DNA target. This represents a shared labor mechanism in which zipping between nucleic acid strands is the actual target recognition mechanism while sensing of the R-loop arrival at the PAM-distal end just verifies the success of the full zipping.

[Ultrasound-guided intermediate cervical plexus block. Anatomical study]

BACKGROUND AND OBJECTIVES

The innervation of the human cervical region is complex and subject to relevant anatomical variability involving sections of the cervical plexus, brachial plexus and cranial nerves.

AIM

The objective was to demonstrate the dissemination of injected dye solution by anatomical preparation and to define a suitable target compartment for an ultrasound-guided block technique.

MATERIAL AND METHODS

Own anatomical preparations are compared to recent review articles on the subject. The focus is on clinically relevant conclusions for performing cervical plexus blocks. In three non-embalmed cadavers six intermediate ultrasound-guided blocks of the cervical plexus were carried out, each with 20 ml methylene blue. Following preparation of the cervical plexus photographic documentation of the spread of the injected marker was performed.

RESULTS

In five cases the target compartment was correctly identified. In these cases, a cranio-caudal spread of the injectate within the double layer of the cervical fascia was observed. In addition, the superficial layer was permeable to the injected methylene blue. The injection solution disseminated with the sensitive terminal branches of the cervical plexus below the platysma. In all cases an anastomosis (superficial cervical ansa) between the facial nerve (ramus colli) and the cervical plexus (transverse cervical nerve) could be demonstrated. The prevertebral lamina proved to be impermeable to injected methylene blue and no evidence of a porous structure of the prevertebral lamina was found.

CONCLUSION

The compartment between the superficial and the prevertebral layer of the cervical fascia is a suitable target for cervical plexus blocks. This injection site describes an intermediate cervical plexus block. As the compartment contains the sensory terminal branches of the spinal nerves C2-4, it may be referred to as C2-C4 compartment. The cranio-caudal spread of the injectate allows lateromedial needle guidance in the horizontal plane. As the superficial lamina is not a barrier to the injectate an additional subcutaneous infiltration of the nerve area appears dispensable. The prevertebral lamina proved to be impermeable to injected methylene blue. Whether phrenic nerve blocks are preventable with more distal intermediate cervical plexus blocks (selective block of the supraclavicular nerves, e.g. for surgery of the clavicle) must be investigated in clinical trials. The permanent anastomosis (superficial cervical ansa) between the cervical plexus and the ramus colli of the facial nerve provides an anatomically reasonable explanation for inadequate cervical plexus blocks.

Adaptation of the chronic disease self-management program for cancer survivors: feasibility, acceptability, and lessons for implementation

Self-management in chronic disease has been shown to improve patient-reported and health care-related outcomes. However, relatively little information about its utility in cancer survivorship is known. We evaluated the feasibility and acceptability of the delivery of an adaptation of the evidence-based Chronic Disease Self-management Program (Stanford) called Cancer Thriving and Surviving (CTS). Triangulated mixed methods were used to capture baseline characteristics and post-program experiences using a combination of closed- and open-ended survey items; emergent coding and simple descriptive statistics were used to summarize the data. Twenty-seven workshops were delivered by 22 CTS leaders to 244 participants between August 2011 and January 2013 in a variety of settings (48 % community, 30 % health care, 22 % regional/community cancer center). Representing a variety of cancer types, about half the participants were 1-3 years post-diagnosis and 45 % were 4 or more years from diagnosis. Program attendance was high with 84 % of participants attending four or more of the six sessions in the workshop. Overall, 95 % of the participants were satisfied with the program content and leaders, and would recommend the program to friends and family. These results confirm the feasibility and acceptability of delivery of a high-fidelity, peer-led model for self-management support for cancer survivors. Expansion of the CTS represents a powerful tool toward improving health-related outcomes in this at-risk population.

[Werner Leibbrand as psychiatric opponent of National Socialism]

The psychiatrist and medical historian Werner Leibbrand resigned from the Berlin Medical Association after the seizure of power in protest against the exclusion of Jewish colleagues and lost both the license to practice as well as his professional position in the public health service. After the end of the war the American military authorities appointed him as expert witness for the prosecution in the Nürnberg Doctors Trial. In addition to a biographical review, Leibbrand's resolute although still undisputed attitude as ethical expert in the trials will be roughly outlined.

Structure-function relationship of the foam-like pomelo peel (Citrus maxima)-an inspiration for the development of biomimetic damping materials with high energy dissipation

The mechanical properties of artificial foams are mainly determined by the choice of bulk materials and relative density. In natural foams, in contrast, variation to optimize properties is achieved by structural optimization rather than by conscious substitution of bulk materials. Pomelos (Citrus maxima) have a thick foam-like peel which is capable of dissipating considerable amounts of kinetic energy and thus this fruit represents an ideal role model for the development of biomimetic impact damping structures. This paper focuses on the analysis of the biomechanics of the pomelo peel and on its structure-function relationship. It deals with the determination of the onset strain of densification of this foam-like tissue and on how this property is influenced by the arrangement of vascular bundles. It was found here that the vascular bundles branch in a very regular manner-every 16.5% of the radial peel thickness-and that the surrounding peel tissue (pericarp) attains its exceptional thickness mainly by the expansion of existing interconnected cells causing an increasing volume of the intercellular space, rather than by cell division. These findings lead to the discussion of the pomelo peel as an inspiration for fibre-reinforced cast metallic foams with the capacity for excellent energy dissipation.

[Successful use of C1 esterase inhibitor in capillary leak syndrome]

This article reports the successful use of C1 esterase inhibitor in the treatment of capillary leak syndrome. The coincidence of exposure to latex during surgery and medication with ramipril led to prolonged shock complicated by secondary hyperfibrinolysis, capillary leak syndrome and multiple organ failure. Initial treatment according to relevant guidelines failed to stabilize the condition. Treatment was only successful after administration of 1,500 IU of human C1 esterase inhibitor.

The performance of organic and conventional cropping systems in an extreme climate year

The 1999 severe crop season drought in the northeastern US was followed by hurricane-driven torrential rains in September, offering a unique opportunity to observe how managed and natural systems respond to climate-related stress. The Rodale Institute Farming Systems Trial has been operating since 1981 and consists of three replicated cropping systems, one organic manure based (MNR), one organic legume based (LEG) and a conventional system (CNV). The MNR system consists of a 5-year maize–soybean–wheat–clover/hay rotation, the LEG of a 3-year maize–soybean–wheat–green manure, and the CNV of a 5-year maize-soybean rotation. Subsoil lysimeters allowed quantification of percolated water in each system. Average maize and soybean yields were similar in all three systems over the post-transition years (1985–1998). Five drought years occurred between 1984 and 1998 and in four of them the organic maize outyielded the CNV by significant margins. In 1999 all crop systems suffered severe yield depressions; however, there were substantial yield differences between systems. Organic maize yielded 38% and 137% relative to CNV in the LEG and MNR treatments, respectively, and 196% and 152% relative to CNV in the soybean plots. The primary mechanism of the higher yield of the MNR and LEG is proposed to be the higher water-holding capacity of the soils in those treatments, while the lower yield of the LEG maize was due to weed competition in that particular year and treatment. Soils in the organic plots captured more water and retained more of it in the crop root zone than in the CNV treatment. Water capture in the organic plots was approximately 100% higher than in CNV plots during September's torrential rains.

Changes in anticholinergic load from regular prescribed medications in palliative care as death approaches

Although there is an understandable emphasis on the side effects of individual medications, the cumulative effects of medications have received little attention in palliative care prescribing. Anticholinergic load reflects a cumulative effect of medications that may account for several symptoms and adverse health outcomes frequently encountered in palliative care. A secondary analysis of 304 participants in a randomised controlled trial had their cholinergic load calculated using the Clinician-Rated Anticholinergic Scale (modified version) longitudinally as death approached from medication data collected prospectively by study nurses on each visit. Mean time from referral to death was 107 days, and mean 4.8 visits were conducted in which data were collected. Relationships to key factors were explored. Data showed that anticholinergic load rose as death approached because of increasing use of medications for symptom control. Symptoms significantly associated with increasing anticholinergic load included dry mouth and difficulty concentrating (P < 0.05). There were also significant associations with increasing anticholinergic load and decreasing functional status (Australia-modified Karnofsky Performance Scale; and quality of life (P < 0.05). This study has documented in detail the longitudinal anticholinergic load associated with medications used in a palliative care population between referral and death, demonstrating the biggest contributor to anticholinergic load in a palliative care population is from symptom-specific medications, which increased as death approached.

Bericht über das Auftreten einer hereditären Chondrodysplasie bei Jungschafen (Spider Lamb Syndrome)

Gegenstand und Ziel: Bei neonatalen Lämmern und Jungtieren einer Herde von Suffolk-Schafen traten plötzlich progressive skelettale Anomalien auf. Ziel dieser Untersuchung war, klinische und genetische Nachweise auf das Vorliegen einer hereditären Chondrodysplasie bei den Jungtieren durchzuführen. Falldarstellung: Vier betroffene Jungtiere, ein weibliches und drei männliche Lämmer im Alter von zwei bis vier Monaten, wurden zur Abklärung des Krankheitsgeschehens näher untersucht. Ergebnisse: Die Befunde der klinischen und röntgenologischen Untersuchung, die histologische Auswertung des unregelmäßigen Wachstums in den Röhrenknochen sowie der genetische Nachweis bestätigten das Vorliegen einer hereditären Chondrodysplasie, des so genannten “Spider Lamb Syndrome”. Klinische Relevanz: In der vorliegenden Arbeit werden die Befunde der klinischen, röntgenologischen, postmortalen und genetischen Untersuchungen präsentiert, der derzeitige Stand der Wissenschaft dokumentiert und die züchterischen Konsequenzen diskutiert.

[Cystic lesion of the dorsal mediastinum]

We present the case of a 52-year-old male who underwent thoracotomy for resection of a suspected bronchogenic cyst in the right posterior mediastinum. The size of the tumor had increased over years, according to repeated X-rays, and the cyst became symptomatic with obstruction of the right subclavian and jugular veins. To our surprise, histopathology revealed a hydatid cyst.

Magnetresonanztomographie in der Urologie

Due to low costs and common availability, ultrasonography and computed tomography still represent the most common diagnostic tools in uroradiology. However, magnetic resonance imaging (MRI) is gaining more and more importance since this imaging modality allows for a comprehensive examination of almost the complete spectrum of urologic diseases, including congenital malformations. The most important advantages of MRI are the free choice of slice orientation, high soft tissue contrast and high resolution as well as the lack of radiation. Technical progresses in hard and software components have led to a reduction in acquisition time, allowing for real-time imaging as well as MR angiography and MR urography with a significant reduction in motion artifacts. In addition, contrast enhanced MRI represents the imaging modality of choice in patients with reduced renal function or known allergy against iodinated contrast agent.

Lymphangioma of the pancreas and the duodenal wall: MR imaging findings

Pancreatic lymphangiomas are rare benign tumours with a histogenesis not yet completely understood. Predominantly the cystic aspect of this lesion can complicate the differentiation from other neoplastic and non-neoplastic cystic tumours of the pancreas. We present a case of a middle-aged woman with a lymphangioma involving the duodenal wall and the pancreatic head. With special regard to MR imaging findings differential diagnosis is discussed.

The chaperone function of ClpB from Thermus thermophilus depends on allosteric interactions of its two ATP-binding sites

ClpB belongs to the Hsp100 family and assists de-aggregation of protein aggregates by DnaK chaperone systems. It contains two Walker consensus sequences (or P-Loops) that indicate potential nucleotide binding domains (NBD). Both domains appear to be essential for chaperoning function, since mutation of the conserved lysine residue of the GX(4)GKT consensus sequences to glutamine (K204Q and K601Q) abolishes its properties to accelerate renaturation of aggregated firefly luciferase. The underlying biochemical reason for this malfunction appears not to be a dramatically reduced ATPase activity of either P-loop per se but rather changed properties of co-operativity of ATPase activity connected to oligomerization properties to form productive oligomers. This view is corroborated by data that show that structural stability (as judged by CD spectroscopy) or ATPase activity at single turnover conditions (at low ATP concentrations) are not significantly affected by these mutations. In addition nucleotide binding properties of wild-type protein and mutants (as judged by binding studies with fluorescent nucleotide analogues and competitive displacement titrations) do not differ dramatically. However, the general pattern of formation of stable, defined oligomers formed as a function of salt concentration and nucleotides and more importantly, cooperativity of ATPase activity at high ATP concentrations is dramatically changed with the two P-loop mutants described.

Regulation of ATPase and chaperone cycle of DnaK from Thermus thermophilus by the nucleotide exchange factor GrpE

The nucleotide binding and release cycle of the molecular chaperone DnaK is regulated by the accessory proteins GrpE and DnaJ, also called co-chaperones. The concerted action of the nucleotide exchange factor GrpE and the ATPase-stimulating factor DnaJ determines the ratio of the two nucleotide states of DnaK, which differ in their mode of interaction with unfolded proteins. In the Escherichia coli system, the stimulation by these two antagonists is comparable in magnitude, resulting in a balance of the two nucleotide states of DnaK(Eco) in the absence and the presence of co-chaperones. The regulation of the DnaK chaperone system from Thermus thermophilus is apparently substantially different. Here, DnaJ does not stimulate the DnaK-mediated ATP hydrolysis and thus does not appear to act as an antagonist of the nucleotide exchange factor GrpE(Tth). This raises the question of whether T. thermophilus GrpE stimulates nucleotide exchange to a smaller degree as compared to the E. coli system and how the corresponding rates relate to intrinsic ATPase and ATP binding as well as luciferase refolding kinetics of T. thermophilus DnaK. We determined dissociation constants as well as kinetic constants that describe the interactions between the T. thermophilus molecular chaperone DnaK, its nucleotide exchange factor GrpE and the fluorescent ADP analogue N8-(4-N'-methylanthraniloylaminobutyl)-8-aminoadenosine-5'-diphosphate by isothermal equilibrium titration calorimetry and stopped-flow kinetic experiments and investigated the influence of T. thermophilus DnaJ on the DnaK nucleotide cycle. The interaction of GrpE with the DnaK.ADP complex versus nucleotide-free DnaK can be described by a simple equilibrium system, where GrpE reduces the affinity of DnaK for ADP by a factor of about 10. Kinetic experiments indicate that the maximal acceleration of nucleotide release by GrpE is 80,000-fold at a saturating GrpE concentration. Our experiments show that in T. thermophilus, although the thermophilic DnaK system displays no stimulation of the DnaK-ATPase activity by DnaJ, nucleotide exchange is still efficiently stimulated by GrpE. This indicates that two counteracting factors are not absolutely necessary to maintain a functional and regulated chaperone cycle. This conclusion is corroborated by data that show that the slower ATPase cycle of the DnaK system as well as of heterologous T. thermophilus DnaK/E. coli DnaK systems is directly reflected in altered refolding kinetics of firefly luciferase but not necessarily in refolding yields.