Precise estimation of postoperative cup alignment from single standard X-ray radiograph with gonadal shielding

This paper addresses the problem of estimating postoperative cup alignment from single standard X-ray radiograph with gonadal shielding. The widely used procedure of evaluation of cup orientation following total hip arthroplasty using single standard anteroposterior radiograph is known inaccurate, largely due to the wide variability in individual pelvic position relative to X-ray plate. 2D-3D image registration methods have been introduced to estimate the rigid transformation between a preoperative CT volume and postoperative radiograph(s) for an accurate estimation of the postoperative cup alignment relative to an anatomical reference extracted from the CT data. However, these methods require either multiple radiographs or a radiograph-specific calibration, both of which are not avaiable for most retrospective studies. Furthermore, these methods were only evaluated on X-ray radiograph(s) without gonadal shielding. In this paper, we propose to use a hybrid 2D-3D registration scheme combining an iterative landmark-to-ray registration with a 2D-3D intensity-based registration to estimate the rigid transfromation for a precise estimation of cup alignment. Quantitative and qualitative results evaluated on clinical and cadaveric datasets are given which indicate the validity of our approach.

Ultrasound-guided needle positioning in sensory nerve conduction study of the sural nerve

OBJECTIVES: To evaluate the usefulness of ultrasound imaging to improve the positioning of the recording needle for nerve conduction studies (NCS) of the sural nerve. METHODS: Orthodromic NCS of the sural nerve was performed in 44 consecutive patients evaluated for polyneuropathy. Ultrasound-guided needle positioning (USNP) was compared to conventional "blind" needle positioning (BNP), electrically guided needle positioning (EGNP), and to recordings with surface electrodes (SFN). RESULTS: The mean distance between the needle tip and the nerve was 1.1 mm with USNP compared to 5.1 mm with BNP (p<0.0001). The mean amplitude of the sensory nerve action potential (SNAP) was 21 microV with USNP and 11 microV with BNP (p<0.0001). Compared to BNP, nerve-needle distances and SNAP amplitudes did not improve with EGNP. SNAP amplitudes recorded with SFN were significantly smaller than with BNP, EGNP and USNP. CONCLUSION: Ultrasound increases the precision of needle positioning markedly, compared to conventional methods. The amplitude of the recorded SNAP is usually clearly greater using USNP. In addition, USNP is faster, less painful and less dependent on the patient. SIGNIFICANCE: USNP is superior to BNP, EGNP, and SFN in accurate measurement of SNAP amplitude. It has a potential use in the routine near-nerve needle sensory NCS of pure sensory nerves.

Relative positioning of diazepam in the benzodiazepine-binding-pocket of GABA receptors

GABA(A) receptors are the major inhibitory neurotransmitter receptors in the brain. Some of them are targets of benzodiazepines that are widely used in clinical practice for their sedative/hypnotic, anxiolytic, muscle relaxant and anticonvulsant effects. In order to rationally separate these different drug actions, we need to understand the interaction of such compounds with the benzodiazepine-binding pocket. With this aim, we mutated residues located in the benzodiazepine-binding site individually to cysteine. These mutated receptors were combined with benzodiazepine site ligands carrying a cysteine reactive group in a defined position. Proximal apposition of reaction partners will lead to a covalent reaction. We describe here such proximity-accelerated chemical coupling reactions of alpha(1)S205C and alpha(1)T206C with a diazepam derivative modified at the C-3 position with a reactive isothiocyanate group (-NCS). We also provide new data that identify alpha(1)H101C and alpha(1)N102C as exclusive sites of the reaction of a diazepam derivative where the -Cl atom is replaced by a -NCS group. Based on these observations we propose a relative positioning of diazepam within the benzodiazepine-binding site of alpha(1)beta(2)gamma(2) receptors.

Theorizing positioning strategies of secondary capital cities

Capital cities that are not the economic centers of their nations – so-called secondary capital cities (SSCs) – tend to be overlooked in the field of political science. Consequentially, there is a lack of research and resulting theory describing their political economy. This paper proposes a comparative research framework which analyzes how external pressures are influencing the relevant policy makers in the process of (re)positioning the SCC.