Outcome of subtalar arthrodesis after calcaneal fracture.

Between 1983 and 1995, we used subtalar arthrodesis to treat 16 consecutive patients for continued pain after an intra-articular calcaneal fracture. Average time to union was 3 months (2 to 4 months). Complications were minor in 4 patients, and major in 4 others. Length of follow-up in 14 patients was 55 months (range, 12 to 112 months). Hindfoot scores (clinical rating system of the American Orthopaedic Foot and Ankle Society) improved from 38 (range, 28 to 62) to 67 (range, 39 to 94). Results of medical outcome surveys indicate that patients had low scores in areas related to physical conditioning, physical role functioning, and bodily pain. We conclude that the majority of patients can have improvement with surgical reconstruction that addresses a specific problem, but pain relief is usually not complete.

The morphological conditions of the permanent pacemaker lead extraction.

Pacemaker lead extraction is the treatment of choice in infectious complications regarding implantation procedure. The purpose of this study was to estimate the safety of the extraction in relation to the morphological changes of the pacing electrode. Research was carried out on materials consisting of 60 human hearts from 45 to 95 years of age (average 63 +/- 15 yrs), with VVI or DDD pacing (pacing duration 84 +/- 26 months) fixed in a formalin solution. Classical macroscopic anatomical methods were applied. In 44 hearts (73.3%) from the investigated group the posterior tricuspid leaflet was thickened only, and in 24 of these hearts the process regarded not only posterior leaflet but also the septal one and especially commissure between them. In 52 hearts (86.6%) inflammatory reaction spread also to the neighbouring part of the electrode. The length of the neointima-inflammatory tissue ranged from 4 to 8 mm (average 5 +/- 2 mm). On the tip of the electrode in the right ventricle cavity in 56 hearts (93.3%) we observed that endocardial leads were surrounded by fibrous thickening, and partially covered by endocardial tissue. We concluded that from the anatomical point of view the extraction of the pacing electrode seems to be questionable, especially in long-term permanent pacing. The experimental traction shows that only recently implanted electrodes were removed without any complications and in others with fraction of the tip, myocardial tissue avulsion or such removal was not successful at all.

split ends encodes large nuclear proteins that regulate neuronal cell fate and axon extension in the Drosophila embryo.

split ends (spen) encodes nuclear 600 kDa proteins that contain RNA recognition motifs and a conserved C-terminal sequence. These features define a new protein family, Spen, which includes the vertebrate MINT transcriptional regulator. Zygotic spen mutants affect the growth and guidance of a subset of axons in the Drosophila embryo. Removing maternal and zygotic protein elicits cell-fate and more general axon-guidance defects that are not seen in zygotic mutants. The wrong number of chordotonal neurons and midline cells are generated, and we identify defects in precursor formation and EGF receptor-dependent inductive processes required for cell-fate specification. The number of neuronal precursors is variable in embryos that lack Spen. The levels of Suppressor of Hairless, a key transcriptional effector of Notch required for precursor formation, are reduced, as are the nuclear levels of Yan, a transcriptional repressor that regulates cell fate and proliferation downstream of the EGF receptor. We propose that Spen proteins regulate the expression of key effectors of signaling pathways required to specify neuronal cell fate and morphology.

A genetic screen for novel components of the Ras/Mitogen-activated protein kinase signaling pathway that interact with the yan gene of Drosophila identifies split ends, a new RNA recognition motif-containing protein.

The receptor tyrosine kinase (RTK) signaling pathway is used reiteratively during the development of all multicellular organisms. While the core RTK/Ras/MAPK signaling cassette has been studied extensively, little is known about the nature of the downstream targets of the pathway or how these effectors regulate the specificity of cellular responses. Drosophila yan is one of a few downstream components identified to date, functioning as an antagonist of the RTK/Ras/MAPK pathway. Previously, we have shown that ectopic expression of a constitutively active protein (yan(ACT)) inhibits the differentiation of multiple cell types. In an effort to identify new genes functioning downstream in the Ras/MAPK/yan pathway, we have performed a genetic screen to isolate dominant modifiers of the rough eye phenotype associated with eye-specific expression of yan(ACT). Approximately 190,000 mutagenized flies were screened, and 260 enhancers and 90 suppressors were obtained. Among the previously known genes we recovered are four RTK pathway components, rolled (MAPK), son-of-sevenless, Star, and pointed, and two genes, eyes absent and string, that have not been implicated previously in RTK signaling events. We also isolated mutations in five previously uncharacterized genes, one of which, split ends, we have characterized molecularly and have shown to encode a member of the RRM family of RNA-binding proteins.

short stop is allelic to kakapo, and encodes rod-like cytoskeletal-associated proteins required for axon extension.

short stop (shot) is required for sensory and motor axons to reach their targets in the Drosophila embryo. Growth cones in shot mutants initiate at the normal times, and they appear normal with respect to overall morphology and their abilities to orient and fasciculate. However, sensory axons are unable to extend beyond a short distance from the cell body, and motor axons are unable to reach target muscles. The shot gene encodes novel actin binding proteins that are related to plakins and dystrophin and expressed in axons during development. The longer isoforms identified are predicted to contain an N-terminal actin binding domain, a long central triple helical coiled-coil domain, and a C-terminal domain that contains two EF-hand Ca(2+) binding motifs and a short stretch of homology to the growth arrest-specific 2 protein. Other isoforms lack all or part of the actin binding domains or are truncated and contain a different C-terminal domain. Only the isoforms containing full-length actin binding domains are detectably expressed in the nervous system. shot is allelic to kakapo, a gene that may function in integrin-mediated adhesion in the wing and embryo. We propose that Shot's interactions with the actin cytoskeleton allow sensory and motor axons to extend.

Risk of avulsion of the Achilles tendon after partial excision for treatment of insertional tendonitis and Haglund's deformity: a biomechanical study.

Surgical treatment of posterior heel pain caused by insertional (calcific) Achilles tendonitis or retrocalcaneal bursitis includes resection of diseased tendon or exostectomy. Currently, no guidelines exist to determine how much tendon may be excised without risking rupture of the Achilles tendon. Anatomic dissections revealed the average height of the insertion measured 19.8 mm (range, 13-25 mm). Average width at the proximal aspect of the insertion measured 23.8 mm (range, 17-30 mm) and distally measured 31.2 (range, 25-38 mm). To assess the risk of avulsion, the tendon insertion was partially released in 25% increments of its measured height or width by one of the four methods: (1) from superior to inferior, (2) from the central portion outward, (3) from medial to lateral, and (4) from lateral to medial. Repeated cyclic loading of body weight x 3 was applied, and, if the tendon remained intact, the next 25% increment was released. This process was repeated until failure occurred. Failure occurred in all specimens by an oblique intratendonous separation or shear between the intact portion remaining on the calcaneus and the resected fibers remaining in the clamp. Fibers inserting into the bone did not avulse. Superior-to-inferior resection was found to be superior to the other three methods with eight of nine specimens remaining intact after 75% resection. We therefore conclude that superior-to-inferior offers the greatest margin of safety when performing partial resections of the Achilles insertion, and as much as 50% of the tendon may be resected safely.

[Should sinus rhythm be restored in patients with chronic atrial fibrillation? Preliminary results from the Polish "Hot Cafe" study]. / Czy przywracac rytm zatokowy u chorych z przewleklym migotaniem przedsionków? Wstepne wyniki polskiego badania "Hot Cafe".

Atrial fibrillation (AF) is the most common arrhythmia occurring in clinical practice. It is the most frequent cause of hospitalization in cardiac rhythm disturbance. Despite comprehensive progress in the research into electrophysiological mechanisms leading to this loss of normal rhythm and new procedures dealing with it, the main problem being the conversion to and maintaining the normal sinus rhythm (SR) has not been solved. The polish study "Hot Cafe" is trying to evaluate the advantages and risks of the two procedures widely used in clinical practice in patients (pts) with chronic AF, i.e. conversion and maintaining SR vs leaving pts with the arrhythmia. Pts with non-valvular chronic AF fulfilling the criteria for including them into the sample are randomly assigned to two procedures: conversion to SR by means of direct current cardioversion and maintaining it or leaving pts with AF. Pts left with AF are treated by rate control and antithrombotic treatment. The project is of prospective kind and it will be carried out by many medical institutions. It is planned to include 200 pts. The observation period will last at least 12 months. Preliminary results after inclusion of the first 121 pts are shown.

Biomechanical evaluation of the schuhli nut.

The schuhli out is a device designed to lock an AO 4.5-mm cortical screw to a 4.5-mm dynamic compression plate independent of bony contact with the plate. The nut engages the screw below the plate, elevating the plate, and locking the screw at a 90 degrees angle, thus preventing toggling. Photoelastic modeling and biomechanical testing on sheep tibias were done to determine the mechanical properties of constructs using schuhli nuts. Use of schuhli nuts was shown to decrease stress in the bone below the plate. The initial axial stiffness of a construct fixed with schuhli nuts is less than a construct with standard screws, but the rate of loss of stiffness with cyclic loading is similar. When a cortical defect is present at the near cortex and the screw engages the far cortex only, the use of a schuhli nut significantly improves the stability of the construct compared with a standard screw alone, and behaves mechanically the same as a standard construct with intact cortices. This indicates that the schuhli nut acts as a substitute for a deficient cortex. The schuhli nut can be useful in osteoporotic bone because it prevents the screw from stripping the threads in the bone as the screw is advanced. It also serves to lock the screw to help prevent the screw from backing out. The schuhli nut may be a useful tool to improve stability in the treatment of complex fractures, reconstructions, or in pathologic bone.