Imprecise Localization Research Articles

Surgical Technique: Computer-generated Custom Jigs Improve Accuracy of Wide Resection of Bone Tumors

Manual techniques of reproducing a preoperative plan for primary bone tumor resection using rudimentary devices and imprecise localization techniques can result in compromised margins or unnecessary removal of unaffected tissue. We examined whether a novel technique using computer-generated custom jigs more accurately reproduces a preoperative resection plan than a standard manual technique. Using CT images and advanced imaging, reverse engineering, and computer-assisted design software, custom jigs were designed to precisely conform to a specific location on the surface of partially skeletonized cadaveric femurs. The jigs were used to perform a hemimetaphyseal resection. We performed CT scans on six matched pairs of cadaveric femurs. Based on a primary bone sarcoma model, a joint-sparing, hemimetaphyseal wide resection was precisely outlined on each femur. For each pair, the resection was performed using the standard manual technique on one specimen and the custom jig-assisted technique on the other. Superimposition of preoperative and postresection images enabled quantitative analysis of resection accuracy. The mean maximum deviation from the preoperative plan was 9.0 mm for the manual group and 2.0 mm for the custom-jig group. The percentages of times the maximum deviation was greater than 3 mm and greater than 4 mm was 100% and 72% for the manual group and 5.6% and 0.0% for the custom-jig group, respectively. Our findings suggest that custom-jig technology substantially improves the accuracy of primary bone tumor resection, enabling a surgeon to reproduce a given preoperative plan reliably and consistently.

CB2 cannabinoid receptors inhibit synaptic transmission when expressed in cultured autaptic neurons

The role of CB2 in the central nervous system, particularly in neurons, has generated much controversy. Fueling the controversy are imperfect tools, which have made conclusive identification of CB2 expressing neurons problematic. Imprecise localization of CB2 has made it difficult to determine its function in neurons. Here we avoid the localization controversy and directly address the question if CB2 can modulate neurotransmission. CB2 was expressed in excitatory hippocampal autaptic neurons obtained from CB1 null mice. Whole-cell patch clamp recordings were made from these neurons to determine the effects of CB2 on short-term synaptic plasticity. CB2 expression restored depolarization induced suppression of excitation to these neurons, which was lost following genetic ablation of CB1. The endocannabinoid 2-arachidonylglycerol (2-AG) mimicked the effects of depolarization in CB2 expressing neurons. Interestingly, ongoing basal production of 2-AG resulted in constitutive activation of CB2, causing a tonic inhibition of neurotransmission that was relieved by the CB2 antagonist AM630 or the diacylglycerol lipase inhibitor RHC80267. Through immunocytochemistry and analysis of spontaneous EPSCs, paired pulse ratios and coefficients of variation we determined that CB2 exerts its function at a presynaptic site of action, likely through inhibition of voltage gated calcium channels. Therefore CB2 expressed in neurons effectively mimics the actions of CB1. Thus neuronal CB2 is well suited to integrate into conventional neuronal endocannabinoid signaling processes, with its specific role determined by its unique and highly inducible expression profile.

Comparative Safety and Efficiency of Five Percutaneous Kidney Biopsy Approaches of Native Kidneys: A Multicenter Study

Background: Renal biopsy (RB) is necessary for the diagnosis, prognosis, and therapy guidance of native kidney diseases. Few studies have compared outcomes of RB procedures. We retrospectively compared the safety and efficiency of five biopsy procedures. Methods: The number of glomeruli on light microscopy (LM) and on immunofluorescence (IF) and serious adverse events following RB performed in five nephrology units (C1–C5) were collected. C1 performed ultrasound (US) assessment before RB and used a 14-gauge core-cutting needle biopsy gun, C2 US guidance and a 14-gauge needle, C3 tomodensitometry guidance and a 14-gauge needle, C4 US guidance and a 16-gauge needle, and C5 tomodensitometry guidance and a 16-gauge needle. Results: RB was performed in 943 adults between January 2006 and July 2010. Serious adverse events occurred in 1.5% of biopsies. The complication rate was not different between nephrology units. The mean number of glomeruli on biopsy was 14.2 ± 8.6 with LM and 4.4 ± 3.3 on IF. It was different according to the nephrology unit for LM (p = 0.01) and for IF (p < 0.001). The number of failed biopsies was influenced by the nephrology unit and radiological guidance technique, favoring real-time US guidance. Failed biopsies using US or tomodensitometry assessment before RB was certainly due to kidney imprecise localization since it was often non-renal tissue sampling. At least 10 glomeruli were found in 69% of biopsies on LM. This rate varied according to the nephrology unit (p = 0.004) and was higher when 14-gauge needles were used in comparison with 16-gauge needles. Conclusion: RB is safe regardless of the technical procedure, but radiological guidance and needle size influence the efficiency of biopsies.

Revision of Molopsis Schatzmayr (Coleoptera: Carabidae: Pterostichini), with descriptions of four new species

The species belonging to the subgenus Molopsis Schatzmayr, 1943 of genus Tapinopterus Schaum, 1858 are revised. Thestudy is based on 372 specimens and includes, for each taxon, diagnosis, description (only for the new species), references,new distributional records and illustrations. Morphological characters of the male and female genitalia are widely used todelimit the separate species, the significance of some non-gonapophyseal genital structures of the females for the system-atics of Molopsis is explicitly emphasized. For the first time, the male genitalia of T. molopiformis, T. molopinus, T. wie-demanni, and T. rebellis, including also newly described species, as well as female genitalia of Molopsis are described andillustrated. All available type material is listed and represented by habitus photographs.As a result, 9 monotypic species of Molopsis are recognized. Tapinopterus rebellis (Chaudoir, 1868) and T. rebelliskumanensis (Reitter, 1884), formerly assigned to Molopsis are recognized as outgroup-taxa. The following new speciesare described: T. (Molopsis) aenigmaticus sp.nov. (Asian Turkey, „Armenia“ imprecise locality), T. (Molopsis) chaudoirisp.nov. (Asian Turkey, Bursa Villayet, Uludağ Mt., Sakarya (Adapazari) Villayet, Gökdağ Mt.), T. (Molopsis) oyukluensissp.nov. (Asian Turkey, Konya Villayet, Fasihan Pass), and T. (Molopsis) relegatus sp.nov. (Asian Turkey, Bolu Villayet,Mengen env., Dorukhan Pass). The following nomenclatural acts are also proposed: Tapinopterus (Molopsis) molopinus (Chaudoir, 1868) = Tapinopterus (Molopsis) dipojranus brussanus Straneo, 1984, syn.nov.; Tapinopterus (Molopsis)

Historical mammal distribution data: How reliable are written records?

Written historical records are widely used to estimate the previous distributions of the larger mammals in southern Africa. However, such records have some limitations and the use of those older than 100 years has been questioned. Written historical records, from the broader Eastern Cape, South Africa, were investigated to examine this contention critically. They were classified according to record quality (acceptability of identification and precision of locality) and analysed according to two levels: ‘all’ species and ‘noticeable’ versus ‘non-noticeable’ species. Records that comprise acceptable identification and precise locality information are the most suitable for mapping historical distributions; they form 33% of the records for the 27 mammal species analysed. A further 49% of the records have acceptable identification but imprecise locality information; they can fulfil a useful function when supported by records where both parameters are of good quality. Thus, the majority (82%) of written historical records from the study area are useful for compiling historical distribution maps and the quality of these records is consistent back to 1750 for this data set. The number and quality of written historical records varies between species. Historical distribution data should be evaluated for reliability (quality) and degree of usefulness, rather than simply discarded a priori.

The genus Chaerilus Simon, 1877 (Scorpiones, Chaerilidae) in the Himalayas and description of a new species

A new species is described belonging to the genus Chaerilus Simon, 1877. Chaerilus annapurna sp. n. was discovered in the high plateaux of the Himalayas in Central-Western Nepal. For comparative purposes a precise re-diagnosis is proposed for Chaerilus truncatus Karsch, 1879, originally described from an imprecise locality in Himalaya. This species has recently been discussed by several authors: nevertheless, it has sometimes been the subject of misidentification.

Functional ANOVA with random functional effects: an application to event-related potentials modelling for electroencephalograms analysis

The differential effects of basic visual or auditory stimuli on electroencephalograms (EEG), named event related potentials (ERPs), are often used to evaluate the impact of treatments on brain performances. In the present paper, we propose a P-splines based model that can be used to evaluate treatment effect on the timing and the amplitude of some peaks of the ERPs curves. Functional ANOVA is an adaptation of linear model or analysis of variance to analyse functional observations. The changes in the functional of interest effects are generally described using smoothing splines. Eilers and Marx proposed to work with P-splines, a combination of B-splines and difference penalties on coefficients. We define a P-splines model for ERPs curves combined with random effects. In particular, we show that it is a useful alternative to classical strategies requiring the visual and usually imprecise localization of specific ERP peaks from curves with a low signal-to-noise ratio.

Magnetic resonance artifact induced by the electrode Activa 3389: an in vitro and in vivo study.

The electrode Activa 3389 is widely implanted for deep brain stimulation (DBS) and MRI is often used to control the position of the electrode. However, induced distorsion artifacts may result in imprecise localization and may lead to misinterpretations of the clinical effects and mechanisms of DBS. In vitro 3D MR study: the proximal and distal contacts of one electrode were spotted by two localizers. The maximal artifact height (MAH) and width (MAW: measured on distal contact), and the distances between the artifact and the localizers (proximal, distal and lateral) were measured on 2 transverse and sagittal MR sequences with 90 degrees rotation of frequency-encoded gradient and phase direction. In vivo 3D MR study: coronal and sagittal reconstructions along the main axis of the electrode were performed on 10 postoperative MR (20 electrodes) to measure MAH and MAW. A Student t test was used to compare in vitro and in vivo measurements. In vitro study: A MAH of 10.35 mm (+/-0.23) and MAW of 3.6 mm (+/-0.2) were found. We measured symmetrical extensions of the artifact over the distal contact. In vivo study: A MAH of 10.36 mm (+/-0.44) and MAW of 3.56 mm (+/-0.30) were obtained. No significant different artifact dimensions were measured between in vitro and in vivo studies (p<0.0001). Precise 3D localization of the electrode in implanted patients is provided by MR identification of the limits of the distal contact artifact. The position of the other contacts is deduced given the size of the contacts and the intercontact distance.

Delivery Strategies to Achieve Therapeutic Myocardial Angiogenesis

The use of recombinant genes or growth factors to enhance myocardial collateral blood vessel function may represent a new approach to the treatment of cardiovascular disease. Proof of concept has been demonstrated in animal models of myocardial ischemia, and clinical trials are underway. Currently, it is unknown which is the safest and most effective delivery strategy to induce clinically important therapeutic angiogenic responses in ischemic myocardium. Most strategies for transcatheter delivery of angiogenic factors have used an intracoronary route, which may have limitations because of imprecise localization of genes or proteins and systemic delivery to noncardiac tissue. The effect of direct intraoperative intramyocardial injection of angiogenic factors on collateral function has been reported in experimental models, and angiogenesis is being studied after direct intramyocardial injection of angiogenic peptides or plasmid vectors during open heart surgery in patients. Catheter-based transendocardial injection of angiogenic factors may provide equivalent benefit without the need for surgery. Intrapericardial delivery of angiogenic factors may offer a theoretical advantage of prolonged exposure of either coronary or myocardial tissue to the administered drug as result of a reservoir function of the pericardium. In this article, we review the different modes of administration for therapeutic myocardial angiogenesis therapy.

Source modelling of the rolandic focus

In rolandic epilepsy, consideration of the stereotyped ictal symptomatology suggests that the epileptic zone is likely to be in the same cortical structure in different patients. Routine EEG tracings of the interictal spike activity suggests a deep Sylvian fissure location. On the basis of the predominantly tangential potential field at the peak spike negativity seen in this group of patients, the inferior bank of the Sylvian fissure appears to be a good candidate. Without invasive studies, little refinement to this rather imprecise localization can be made as there is neither neurologic deficit nor lesion to provide a marker on radiological imaging. However, the application of source modelling technique using a simple single-dipole spherical head model has resulted in improved understanding of the generator behaviour, and facilitated the generation of new ways of analyzing spikes (e.g., stability index). Review of newer quantitative approaches including matrix and singular value decomposition of the dataset, spatial-temporal constrained source estimates etc. suggest other fruitful approaches. At least in some patients with partial epilepsy, the source characteristics of interictal scalp spikes appear to contain information of the ictal generator. Under certain circumstances, such derived information which is not otherwise available from routine electrophysiology may influence clinical management and prognosis. This is an additional bonus to the primary objectives of quantification and data reduction.

Perceptual localization of visual stimuli flashed during saccades.

Subjects were asked to make a saccade to a visual target flashed in the dark during a prior primary saccade, and to report its apparent position by moving an adjustable light spot to that position. When targets were presented at the beginning of the primary saccade, subjects perceptually mislocated them in the direction of the saccade, whereas when targets were presented immediately before the end of the primary saccade, the flashed targets were mislocated in the opposite direction. The perceptually localized position of the target was primarily determined by its retinal position. However, at all actual and retinal positions of the target, the localized position shifted from the position that would be predicted if the location of the target was determined only by its retinal position to the prior primary saccade direction. The results were discussed in relation to extraretinal eye position signals. Subjects moved their eyes not to the actual position of the target, but to its apparent position. In some trials, there was a discrepancy between perceptual and oculomotor localization, which was interpreted as having been caused by the imprecise localization ability of the oculomotor system.

Immunoelectron microscopic localization of glomerular IgA deposits using a protein A-colloidal gold probe.

Currently there is increasing interest in the localization and accurate determination of the composition of protein deposits involved in the pathogenesis of human glomerulonephritis using immunoelectron microscopy. Previous studies have largely relied on capricious immunoperoxidase techniques applying both the preembedding and postembedding methods to renal tissue. Both methods identify a single antigen, but preservation of ultrastructure is suboptimal, and there is the potential problem of imprecise localization of antigen due to diffusion of the peroxidase reaction product. A less demanding method of ultrastructural antigen identification for renal tissue has been employed with success in clearly localizing glomerular deposits of IgA. The technique involves fixation of tissue in periodate-lysine-paraformaldehyde, embedding in L. R. White resin, and labeling by an indirect immunologic reaction using protein A-gold as an electron-dense marker. This technique provides an accurate marker for the localization of glomerular antigen while retaining optimal tissue morphology, and we predict that this method will have wide application in human and experimental renal disease.

Endothelium and "silver lines". An electron microscopic study.

The significance of endothelial "silver lines" was studied by TEM in rat aortas after perfusion with glutaraldehyde followed by silver nitrate. Standard TEM technique proved unsatisfactory (coarse silver granules, imprecise localization, artefacts). Exposure of the silver-treated aortas to photographic fixer markedly improved the image of the deposits leaving fine, stable, uniform "residual granules" about 100 A in diameter. Most of these granules were localized along the intercellular junctions; they also tended to pool in the basement membrane beneath each junction. This image suggests that the Ag+ ions pass through the junction, and react with its contents as well as with the basement membrane beyond it. A scheme is proposed to explain the reaction of Ag+ ions with anions and negatively charged radicals within the junction. It is concluded that the "silver lines" represent not only a histochemical effect, but also the visualization of a transendothelial electrolyte pathway.