Rationales for the Bernese approaches in acetabular surgery

PURPOSE: To present two new approaches to acetabular surgery that were established in Berne, and which aim at enhanced visualization and anatomical reconstruction of acetabular fractures. METHOD: The trochanteric flip osteotomy allows for surgical hip dislocation, and was introduced as a posterior approach for acetabular fracture management involving the posterior column and wall. For acetabular fractures predominantly involving the anterior column and the quadrilateral plate, the Pararectus approach is described. RESULTS: Full exposure of the hip joint, as provided by the trochanteric flip osteotomy, facilitates anatomical reduction of acetabular or femoral head fractures and safe positioning of the anterior column screw in transverse or T-shaped fractures. Additionally, the approach enables osteochondral transplantation as a salvage procedure for severe chondral femoral head damage and osteoplasty of an associated inadequate offset at the femoral head-neck junction. The Pararectus approach allows anatomical restoration with minimal access morbidity, and combines advantages of the ilioinguinal and modified Stoppa approaches. CONCLUSIONS: Utilization of the trochanteric flip osteotomy eases visualization of the superior aspect of the acetabulum, and enables the evaluation and treatment of chondral lesions of the femoral head or acetabulum and labral tears. Displaced fractures of the anterior column with a medialized quadrilateral plate can be addressed successfully through the Pararectus approach, in which surgical access is associated with minimal morbidity. However, long-term results following the two presented Bernese approaches are needed to confirm that in the treatment of complex acetabular fractures the rate of poor results in almost one-third of all cases (as currently yielded using traditional approaches) might be reduced by the utilization of the presented novel approaches.

Novel, potent, and radio-iodinatable somatostatin receptor 1 (sst1) selective analogues

The proposed sst(1) pharmacophore (J. Med. Chem. 2005, 48, 523-533) derived from the NMR structures of a family of mono- and dicyclic undecamers was used to design octa-, hepta-, and hexamers with high affinity and selectivity for the somatostatin sst(1) receptor. These compounds were tested for their in vitro binding properties to all five somatostatin (SRIF) receptors using receptor autoradiography; those with high SRIF receptor subtype 1 (sst(1)) affinity and selectivity were shown to be agonists when tested functionally in a luciferase reporter gene assay. Des-AA(1,4-6,10,12,13)-[DTyr(2),DAgl(NMe,2naphthoyl)(8),IAmp(9)]-SRIF-Thr-NH(2) (25) was radio-iodinated ((125)I-25) and specifically labeled sst(1)-expressing cells and tissues. 3D NMR structures were calculated for des-AA(1,4-6,10,12,13)-[DPhe(2),DTrp(8),IAmp(9)]-SRIF-Thr-NH(2) (16), des-AA(1,2,4-6,10,12,13)-[DAgl(NMe,2naphthoyl)(8),IAmp(9)]-SRIF-Thr-NH(2) (23), and des-AA(1,2,4-6,10,12,13)-[DAgl(NMe,2naphthoyl)(8),IAmp(9),Tyr(11)]-SRIF-NH(2) (27) in DMSO. Though the analogues have the sst(1) pharmacophore residues at the previously determined distances from each other, the positioning of the aromatic residues in 16, 23, and 27 is different from that described earlier, suggesting an induced fit mechanism for sst(1) binding of these novel, less constrained sst(1)-selective family members.

What's Happening? Allan Kaprow and Claes Oldenburg Argue About Art And Life

In 1961 Allan Kaprow (1927–2006) and Claes Oldenburg (b. 1929) exchanged a number of letters in which they argued about the definition of their avant-garde practices as Happenings. Kaprow, who first introduced this "root-metaphor," as he would later call it, describes with it the necessity of the respective activity to be as far removed as possible from all motives, materials, and formats conventionally connected to art. Oldenburg, who at the time of this exchange was just as active in the New York performance scene as Kaprow, disagrees with his colleague's removal of their practice from the artistic sphere. Oldenburg is also dissatisfied with the fact that Kaprow, through his writings, launches a critical discourse that follows his own definition of the Happening. The two artists thus argue just as much about the positioning of their practices with respect to art as over the authority to establish such a position. This essay traces their argument through their written conversation and in doing so exposes the immense influence Kaprow's rhetoric had on the subsequent art-historical canonization of their respective practices: Oldenburg's more ambivalent position is today amalgamated with Kaprow's theoretical stance.

Oligodeoxynucleotide Duplexes Containing (5′S)-5′-C-Alkyl-Modified 2′-Deoxynucleosides: Can an Alkyl Zipper across the DNA Minor-Groove Enhance Duplex Stability?

10.1002/hlca.200390311.abs A series of oligonucleotides containing (5′S)-5′-C-butyl- and (5′S)-5′-C-isopentyl-substituted 2′-deoxyribonucleosides were designed, prepared, and characterized with the intention to explore alkyl-zipper formation between opposing alkyl chains across the minor groove of oligonucleotide duplexes as a means to modulate DNA-duplex stability. From four possible arrangements of the alkyl groups that differ in the density of packing of the alkyl chains across the minor groove, three (duplex types I–III, Fig. 2) could experimentally be realized and their duplex-forming properties analyzed by UV-melting curves, CD spectroscopy, and isothermal titration calorimetry (ITC), as well as by molecular modeling. The results show that all arrangements of alkyl residues within the minor groove of DNA are thermally destabilizing by 1.5–3°/modification in Tm. We found that, within the proposed duplexes with more loosely packed alkyl groups (type-III duplexes), accommodation of alkyl residues without extended distorsion of the helical parameters of B-DNA is possible but does not lead to higher thermodynamic stability. The more densely packed and more unevenly distributed arrangement (type-II duplexes) seems to suffer from ecliptic positioning of opposite alkyl groups, which might account for a systematic negative contribution to stability due to steric interactions. The decreased stability in the type-III duplexes described here may be due either to missing hydrophobic interactions of the alkyl groups (not bulky enough to make close contacts), or to an overcompensation of favorable alkyl-zipper formation presumably by loss of structured H2O in the minor groove.

Komplikationen beim kathetergestützten Aortenklappenersatz nach transfemoralem Zugang

Hintergund Seit mehr als 10 Jahren wird der kathetergestützte Aortenklappenersatz (Transkatheter-Aortenklappenimplantation, „transcatheter aortic valve implantation“, TAVI) durchgeführt. Bereits in der Anfangsphase haben sich eingriffstypische Komplikationen nach transfemoralem Zugang herauskristallisiert. Ziel der Arbeit Beispielhaft wird anhand von 4 Sektionsfällen beschrieben, wie die Indikationsstellung zur TAVI und die Vermeidbarkeit der Komplikation zu prüfen ist. Material und Methoden Bei einer 86-jährigen Frau war es im Rahmen eines Repositionsversuchs des Implantats zu einem Abriss der rechten Beckengefäße gekommen. Bei einer 82-jährigen Frau war es während der Intervention zu einem Einriss des Aortenklappenrings mit Perikardtamponade gekommen. Eine 89-jährige Frau erlitt während der Intervention eine gedeckte Aortenverletzung und war während der anschließenden operativen Versorgung des Defekts verstorben. Im vierten Fall war bei einer 83 Jahre alt gewordenen Patientin im Rahmen des transfemoralen Klappenersatzes die Positionierung der Klappe misslungen, und ventrikelwärts entwickelte sich eine Embolisation der entfalteten Klappe. Es wurde eine zweite gleichartige Klappe positioniert, die in der Aorta hielt. Ergebnisse Die Indikationsstellung zur TAVI war in den 4 Fällen der multimorbiden Patientinnen gerechtfertigt. Die Komplikationen waren sehr unterschiedlich und die Gefäßverletzungen in 2 Fällen aufgrund der begonnenen Operationen nicht mehr zu prüfen. Schlussfolgerungen Die Versorgung einer Komplikation ist beim indikationsgerechten Patientenkollektiv aufgrund der Multimorbidität extrem schwierig und mit zahlreichen weiteren Komplikationen behaftet. Schlüsselwörter Herzklappenerkrankungen – Herzklappenprothese – Minimalinvasive Verfahren – Behandlungsfehler – Inoperabilität

A Neuromonitoring Approach to Facial Nerve Preservation During Image-guided Robotic Cochlear Implantation.

HYPOTHESIS A multielectrode probe in combination with an optimized stimulation protocol could provide sufficient sensitivity and specificity to act as an effective safety mechanism for preservation of the facial nerve in case of an unsafe drill distance during image-guided cochlear implantation. BACKGROUND A minimally invasive cochlear implantation is enabled by image-guided and robotic-assisted drilling of an access tunnel to the middle ear cavity. The approach requires the drill to pass at distances below 1 mm from the facial nerve and thus safety mechanisms for protecting this critical structure are required. Neuromonitoring is currently used to determine facial nerve proximity in mastoidectomy but lacks sensitivity and specificity necessaries to effectively distinguish the close distance ranges experienced in the minimally invasive approach, possibly because of current shunting of uninsulated stimulating drilling tools in the drill tunnel and because of nonoptimized stimulation parameters. To this end, we propose an advanced neuromonitoring approach using varying levels of stimulation parameters together with an integrated bipolar and monopolar stimulating probe. MATERIALS AND METHODS An in vivo study (sheep model) was conducted in which measurements at specifically planned and navigated lateral distances from the facial nerve were performed to determine if specific sets of stimulation parameters in combination with the proposed neuromonitoring system could reliably detect an imminent collision with the facial nerve. For the accurate positioning of the neuromonitoring probe, a dedicated robotic system for image-guided cochlear implantation was used and drilling accuracy was corrected on postoperative microcomputed tomographic images. RESULTS From 29 trajectories analyzed in five different subjects, a correlation between stimulus threshold and drill-to-facial nerve distance was found in trajectories colliding with the facial nerve (distance <0.1 mm). The shortest pulse duration that provided the highest linear correlation between stimulation intensity and drill-to-facial nerve distance was 250 μs. Only at low stimulus intensity values (≤0.3 mA) and with the bipolar configurations of the probe did the neuromonitoring system enable sufficient lateral specificity (>95%) at distances to the facial nerve below 0.5 mm. However, reduction in stimulus threshold to 0.3 mA or lower resulted in a decrease of facial nerve distance detection range below 0.1 mm (>95% sensitivity). Subsequent histopathology follow-up of three representative cases where the neuromonitoring system could reliably detect a collision with the facial nerve (distance <0.1 mm) revealed either mild or inexistent damage to the nerve fascicles. CONCLUSION Our findings suggest that although no general correlation between facial nerve distance and stimulation threshold existed, possibly because of variances in patient-specific anatomy, correlations at very close distances to the facial nerve and high levels of specificity would enable a binary response warning system to be developed using the proposed probe at low stimulation currents.

New Self-Expanding Transcatheter Valve for Off-Pump Transatrial Mitral Valve-In-Ring Implantation.

OBJECTIVES To validate a self-expanding transcatheter valve for off-pump transatrial mitral valve-in-ring (VIR) implantation via a left thoracotomy. METHODS Mitral valve annuloplasty was performed via sternotomy during cardiopulmonary bypass on 9 pigs. After successful weaning from extracorporal circulation, the custom-made, self-expanding transcatheter VIR device was deployed under fluoroscopic guidance within the annuloplasty ring via a left thoracotomy. Hemodynamic data before and after the implantation were recorded. Mitral annulus diameter and valve area were measured by echocardiography. Transvalvular and left-ventricular outflow-tract pressure gradient were measured invasively. RESULTS Eight successful implantations were performed. Implantation failed in 1 pig because of difficulty with technical delivery of the sheath. Mean transatrial procedure time was 12.6 ± 1.7 min. Hemodynamic status during transatrial implantation was stable, and differences were not statistically significant. Mean mitral annulus diameter and mean mitral orifice area were 2.32 ± 0.2 and 3.84 ± 0.55 cm2, respectively. Mild regurgitation was detected in 7 animals and moderate regurgitation in 1. Mean gradients were 6.1 ± 5.0 mm Hg across the device. Postmortem examination confirmed adequate positioning of devices within the annuloplasty ring. CONCLUSIONS This custom-made transcatheter device allows for safe and reproducible off-pump transatrial mitral VIR implantations. Transatrial access is a promising route to facilitate VIR implantations. Our custom-made stent-valve may be suitable for VIR procedures.

Reproducibility of sensory nerve conduction studies of the sural nerve using ultrasound-guided needle positioning

In this study we sought to evaluate the reproducibility of sensory nerve conduction studies (NCS) using ultrasound-guided needle positioning (USNP).

Percutaneous radiofrequency ablation of virtual tumours in canine kidney using Global Positioning System-like technology

What's known on the subject? And what does the study add? We have previously shown that percutaneous radiofrequency ablation guided by image-fusion technology allows for precise needle placement with real time ultrasound superimposed with pre-loaded imaging, removing the need for real-time CT or MR guidance. Emerging technology also allows real-time tracking of a treatment needle within an organ in a virtually created 3D format. To our knowledge, this is the first study utilising a sophisticated ultrasound-based navigation system that uses both image-fusion and real-time probe-tracking technologies for in-vivo renal ablative intervention.

Radiation exposure in whole-body computed tomography of multiple trauma patients: bearing devices and patient positioning

Whole-body computed tomography (WBCT) plays an important role in the management of severely injured patients. We evaluated the radiation exposure of WBCT scans using different positioning boards and arm positions.

Impact of subunit positioning on GABAA receptor function

The major isoforms of the GABAA (gamma-aminobutyric acid type A) receptor are composed of two alpha, two beta and one gamma subunit. Thus alpha and beta subunits occur twice in the receptor pentamer. As it is well documented that different isoforms of alpha and beta subunits can co-exist in the same pentamer, the question is raised whether the relative position of a subunit isoform affects the functional properties of the receptor. We have used subunit concatenation to engineer receptors of well-defined subunit arrangement to study this question. Although all five subunits may be concatenated, we have focused on the combination of triple and dual subunit constructs. We review here what is known so far on receptors containing simultaneously alpha1 and alpha6 subunits and receptors containing beta1 and beta2 subunits. Subunit concatenation may not only be used to study receptors containing two different subunit isoforms, but also to introduce a point mutation into a defined position in receptors containing either two alpha or beta subunits, or to study the receptor architecture of receptors containing unconventional GABAA receptor subunits. Similar approaches may be used to characterize other members of the pentameric ligand-gated ion channel family, including nicotinic acetylcholine receptors, glycine receptors and 5-HT3 (5-hydroxytryptamine) receptors.

A GABA(A) receptor of defined subunit composition and positioning: concatenation of five subunits

We show that the five subunits of a gamma-aminobutyric acid type A receptor (GABA(A) receptor) can be concatenated to yield a functional receptor. This concatenated receptor alpha(1)-beta(2)-alpha(1)-gamma(2)-beta(2) has the advantage of a known subunit arrangement. Most of its functional properties are not significantly different from a receptor formed by individual subunits. Extent of expression amounted to about 40% of that of non-concatenated receptors in Xenopus oocytes, after injection of oocytes with comparable amounts of cRNA coding for concatenated and non-concatenated receptors. The ability to express receptors consisting of five subunits enables detailed studies of GABA(A) receptor subtype selective compounds.