Apparent Migration Research Articles

Vascular Precursors in Developing Human Retina

Prior investigation has demonstrated that angioblasts are present in the inner retinas of human embryos and fetuses and that they differentiate and organize to form the primordial retinal vasculature. The purpose of this study was to characterize these angioblasts further and examine ligands that might control their migration and differentiation. Immunohistochemistry was used to localize stroma-derived factor-1 (SDF-1), its receptor CXCR4, stem cell factor (SCF), and its receptor c-Kit on sections obtained from human eyes at from 6 to 23 weeks' gestation (WG). Coexpression of CD39 (marker for retinal angioblasts and endothelial cells) and CXCR4 or c-Kit was investigated by confocal microscopy. SDF-1 was prominent in inner retina with the greatest reaction product near the internal limiting membrane (ILM). SCF immunoreactivity was also confined to the inner retina and increased significantly between 7 and 12 WG. The level of both ligands declined by 22 WG. A layer of CXCR4(+) and c-Kit(+) precursors, some of which coexpressed CD39, existed in the inner retina from 7 to 12 WG. With migration, c-Kit was downregulated, whereas CD39(+) cells continued to express CXCR4 as they formed cords. With canalization, CXCR4 expression was downregulated. Embryonic human retina has a pool of precursors (CXCR4(+) and c-Kit(+)) that enlarged centrifugally during fetal development. From this pool emerges angioblasts, which migrate anteriorly into the nerve fiber layer where SDF-1 and SCF levels are highest. c-Kit expression declines with apparent migration, and CXCR4 expression declines with canalization of new vessels. Both SCF and SDF-1 are associated with the differentiation of retinal precursors into angioblasts and their migration to sites of vessel assembly.

Vertical zonation and distributions of calanoid copepods through the lower oxycline of the Arabian Sea oxygen minimum zone

This paper provides the first comprehensive analysis of calanoid copepod vertical zonation and community structure at midwater depths (300–1000 m) through the lower oxygen gradient (oxycline) (0.02 to ∼0.3 ml/L) of an oxygen minimum zone (OMZ). Feeding ecology was also analyzed. Zooplankton were collected with a double 1 m 2 MOCNESS plankton net in day and night vertically-stratified oblique tows from 1000 m to the surface at six stations during four seasons as part of the 1995 US Joint Global Ocean Flux Study (JGOFS) Arabian Sea project. The geographic comparison between a eutrophic more oxygenated onshore station and an offshore station with a strong OMZ served as a natural experiment to elucidate the influence of depth, oxygen concentration, season, food resources, and predators on the copepod distributions. Copepod species and species assemblages of the Arabian Sea OMZ differed in their spatial and vertical distributions relative to environmental and ecological characteristics of the water column and region. The extent and intensity of the oxycline at the lower boundary of the OMZ, and its spatial and temporal variability over the year of sampling, was an important factor affecting distributional patterns. Calanoid copepod species showed vertical zonation through the lower OMZ oxycline. Clustering analyses defined sample groups with similar copepod assemblages and species groups with similar distributions. No apparent diel vertical migration for either calanoid or non-calanoid copepods at these midwater depths was observed, but some species had age-related differences in vertical distributions. Subzones of the OMZ, termed the OMZ Core, the Lower Oxycline, and the Sub-Oxycline, had different copepod communities and ecological interactions. Major distributional and ecological changes were associated with surprisingly small oxygen gradients at low oxygen concentrations. The calanoid copepod community was most diverse in the most oxygenated environments (oxygen >0.14 ml/L), but the rank order of abundance of species was similar in the Lower Oxycline and Sub-Oxycline. Some species were absent or much scarcer in the OMZ Core. Two copepod species common in the Lower Oxycline were primarily detritivorous but showed dietary differences suggesting feeding specialization. The copepod Spinocalanus antarcticus fed primarily on components of the vertical particulate flux and suspended material, a less versatile diet than the co-occurring copepod Lucicutia grandis. Vertical zonation of copepod species through the lower OMZ oxycline is probably a complex interplay between physiological limitation by low oxygen, potential predator control, and potential food resources. Pelagic OMZ and oxycline communities, and their ecological interactions in the water column and with the benthos, may become even more widespread and significant in the future ocean, if global warming increases the extent and intensity of OMZs as predicted.

Marine Migration of North American Green Sturgeon

AbstractAn understanding of the distribution of North American green sturgeon Acipenser medirostris in coastal waters is crucial to minimize impacts on this vulnerable species from various fisheries. To determine migratory patterns, we tagged 213 subadult and adult green sturgeon in spawning rivers and summer aggregation areas with uniquely coded ultrasonic pingers and observed their coastal movements with arrays of automated hydrophones deployed along the West Coast of North America from southeast Alaska to Monterey Bay, California. Green sturgeon exhibited an annual migration along the continental shelf from U.S. to Canadian waters in the fall and an apparent return migration in the spring. Peak migration rates exceeded 50 km/d during the springtime southward migration. Large numbers of green sturgeon were detected near Brooks Peninsula on northwest Vancouver Island, British Columbia, during May‐June and October‐November. A single fish was detected in southeast Alaska in December. This pattern of detections suggests that important overwintering grounds may be north of Vancouver Island and south of Cape Spencer, Alaska. A high frequency of detection allowed us to estimate that annual survival of tagged green sturgeon was 0.83 in 2004. The rapid, frequent long‐distance migrations by these fish may make them vulnerable to bycatch in bottom trawl fisheries on the shelf waters of western North America.

Late Complications Following Macroplastique® Implantation for Urodynamic Stress Incontinence

Two previously unreported complications of Macroplastique® (Uroplasty Ltd., Manchester, UK) implants for urodynamic stress incontinence are described in this paper: the apparent migration of a Macroplastique implant following an inadvertent treatment in early pregnancy and dyspareunia presenting 12 months following a Macroplastique treatment, requiring excisional treatment for symptom relief.

Immobilized phospholipid capillary electrophoresis for study of drug–membrane interactions and prediction of drug activity

Immobilized phospholipid capillary electrophoresis (IPCE) was developed for studying the interactions between a set of nonsteroidal anti-inflammatory drugs (NSAIDs) and membrane and predicting the biological activity of NSAIDs. Supported vesicle layers and supported phospholipid bilayers were attached to the inner surface of a capillary wall simply by rinsing with liposome solutions. The liposomes, composed of soybean phosphatidylcholine (SPC) or SPC and different proportions of cholesterol (Ch), were small unilamellar vesicles prepared by sonication. The normalized capacity factor ( K IPCE) was introduced into IPCE for evaluating drug–membrane interactions. Related theories and equations were derived to calculate K IPCE values from apparent migration time of a solute and electroosmotic flow. The strong relationships were observed between log K IPCE (SPC) values and log K lw values (the partition coefficients determined in free SPC-liposome partitioning system) ( R = 0.9855 and P < 0.0001) or log K ILC values (the normalized capacity factors determined by immobilized POPC-liposome chromatography, POPC represents 1-palmitoyl-2-oleoyl- sn-glycero-3-phosphocholine) ( R = 0.9875 and P < 0.0001). In addition, log K IPCE (SPC/Ch 80:20%) values correlated well with the pIC 50 (the minus logarithm of IC 50) values for cyclooxygenase 2 determined on intact cells ( R = 0.959 and P < 0.001). These results confirmed that IPCE, K IPCE value as evaluation index, can be effectually used for studying drug–membrane interactions and it has the potential to predict drug activity. Cholesterol-containing (20 mol%) liposomes may be more suitable to mimic real cell membrane.

From Proton Disorder to Proton Migration: A Continuum in the Hydrogen Bond of a Proton Sponge in the Solid State

The crystal structure of the ionic complex of 1,8-bis(dimethylamino)naphthalene (DMAN) and 4,5-dichlorophthalic acid has been investigated using a multi-temperature X-ray diffraction approach. The two short intramolecular hydrogen bonds exhibit different behaviors, with the [O···H···O]- hydrogen bond appearing approximately centered throughout the experiment. The [N···H···N]+ hydrogen bond, on the other hand, exhibits a complicated temperature-dependent behavior, with disordered electron density being observed at lower temperatures, with apparent migration at higher temperatures. This continuum can be explained simply in terms of the changing local environment of the [N···H···N]+ hydrogen bond induced by lattice expansion. The related complex of DMAN with 3,4-furandicarboxylic acid shows no equivalent effects; this is consistent with the explanation proposed.

The evolution of hydrogen atom parameters under changing external conditions by time-of-flight single crystal neutron diffraction

Recent studies performed by our group, of hydrogen atom behaviour in hydrogen bonds as a function of external variable, are reviewed. The changes observed, often manifest in the form of proton disorder or apparent migration, open up the intriguing possibility of being able to alter the behaviour of hydrogen bonds. This work has only been made possible by developments in data collection methods that allow evolving molecular structures to be studied at unprecedented numbers of temperatures and pressures by neutron single crystal diffraction. It is shown that even more insight is possible by complementing such studies with imaging of hydrogen bonds using X-ray methods, together with using computational studies to try to shed additional light on the underlying potentials.

Thermal maturity of the Barnett Shale determined from well-log analysis

Intensive development with large-scale fracturing treatments has made the Barnett Shale play (Newark East field) in the Fort Worth Basin the largest shale-gas field in the world. The Mississippian Barnett Shale is an organic-rich, self-sourced reservoir rock. Thermal maturity, thickness, and total organic carbon are the most important geological factors for commercial gas production from this shale formation. The log-derived thermal-maturity index (MI) has been developed in an effort to better understand and predict hydrocarbon phases across the basin. Maturity index was calculated using three types of open-hole logs: neutron porosity, deep resistivity, and density porosity (or bulk density). The derivation of MI is based on the hypotheses that shale gas is generated and stored locally without apparent migration from outside sources, and that the water saturation and the density of generated hydrocarbons decrease with an increase in thermal maturity. Maturity index correlates well with initial gas:oil ratios (GOR) from well production data. Based on this correlation, an empirical relationship has been demonstrated for the Fort Worth Basin. This method is useful in understanding the thermal-maturity levels of Barnett Shale source rock in the gas-generation window. Mapping MI, GOR, and gas heating value from hundreds of wells identifies the various maturity stages and areas of Barnett Shale that generate oil, condensate, wet gas, or dry gas in the Fort Worth Basin.

Experimental study on the ion migration of rod samples for high voltage DC porcelain support insulators

The ion migration testing used for DC porcelain support insulators was carried out in this paper. Ten rod samples for DC porcelain support insulators were subjected to a long-term ion migration testing in our laboratory in accordance with the reported procedure of IEC. The changes of Na <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> distribution along with the samples under the long-term testing were analyzed, compared to that of the untested samples. The mechanical performance of the tested samples was verified by using bending breakdown testing. The research findings indicate that the ion migration testing designed for support insulators does not cause Na <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> ion apparent migration in the samples and does not influence the mechanical performance of the tested samples

A NLRR-1 gene is expressed in migrating slow muscle cells of the trout (Oncorhynchus mykiss) embryo

NLRR-l (neuronal leucine-rich repeat-l) is a transmembrane protein that functions as a cell adhesion molecule regulating morphogenesis. A previous study in the mouse reported that the somitic expression of NLRR-1 is restricted to the dorsal lip of the dermomyotome that gives rise to the epaxial muscle. In this study, we report the expression of a NLRR-1 gene in the trout-developing somite. Whole mount in situ hybridization showed that NLRR-l transcript accumulated in a rostro-caudal wave in the adaxial slow muscle cells, which are initially found deep in the somite, immediately adjacent to the notochord. No labelling was observed in the segmental plate from which somites form. As somites mature along an anteroposterior axis, the NLRR-l-positive adaxial cells exhibited an apparent migration radially to the lateral surface of the myotome where they ultimately form the peripheral slow muscle fibres. These observations show that a NLRR-1 gene is expressed in a subpopulation of myogenic cells of the trout embryo, but the anatomical location and the fate of this subpopulation are distinct from those of the NLRR-1 positive myogenic cells in amniotes. NLRR-l was also transcribed in distinct areas of the developing nervous system including the telencephalon, the optic tectum, the cerebellum, the neural tube, the retina, and the branchial arches.

Isoform-Specific Regulation of the Actin-Organizing Protein Palladin during TGF-β1-Induced Myofibroblast Differentiation

Contractile myofibroblasts are responsible for remodeling of extracellular matrix during wound healing; however, their continued activity results in various fibrocontractive diseases. Conversion of fibroblasts into myofibroblasts is induced by transforming growth factor-beta1 (TGF-beta1) and is hallmarked by the neo-expression of alpha-smooth muscle actin (alpha-SMA), a commonly used myofibroblast marker. Moreover, myofibroblast differentiation and acquisition of the contractile phenotype involves functionally important alterations in the expression of actin-organizing proteins. We investigated whether myofibroblast differentiation is accompanied by changes in the expression of palladin, a cytoskeletal protein that controls stress fiber integrity. Palladin is expressed as several isoforms, including major 3Ig (90 kDa) and 4Ig (140 kDa) forms that differ in their N-terminal sequence. Expression of the 4Ig isoform is strongly induced in fibroblast stress fibers upon TGF-beta1 treatment preceding alpha-SMA upregulation. TGF-beta1 induced upregulation of palladin is mediated both by Smad and mitogen-activated protein kinase pathways. Furthermore, palladin 4Ig-isoform is co-expressed with alpha-SMA in vivo in experimental rat wounds and in human myofibroblast-containing lesions. Taken together these results identify palladin 4Ig as a novel marker of myofibroblast conversion in vitro and in vivo. They also provide for the first time information about the signaling cascades involved in the regulation of palladin expression.

The adhesion of Pseudomonas aeruginosa to high molecular weight human tear film species corresponds to glycoproteins reactive with Sambucus nigra lectin

Pseudomonas aeruginosa is a pathogen gaining prevalence in contact lens-related corneal ulcers. Tear outflow protects the ocular surface, where high molecular weight tear glycoproteins bind bacteria for removal from the eye. The purpose of the present study was to identify glycoproteins in human tears involved in the adhesion of ocular P. aeruginosa isolates. Basal human tears were applied to a bacterial adhesion assay involving electrophoretic separation of tear components, transfer to nitrocellulose and incubation with biotin-labelled bacteria. Glycoproteins were further characterised using lectin profiling. The results showed large-dimension agarose gels were imperative for the detection of at least four glycoproteins with a migration >200 kDa, including species not previously identified. P. aeruginosa 6294 preferentially bound to a well-defined glycoprotein near the origin of the gel that, unlike other glycoproteins >200 kDa, reacted with Sambucus nigra lectin (sialic acid α2–6) but not WGA lectin ( N-acetylglucosamine, sialic acid α2–3). Adhesion did not involve free biotin label or hydrophobic interactions. Also, the pre-incubation of separated tear glycoproteins with S. nigra lectin increased subsequent adhesion of 6294 to this tear glycoprotein. The less virulent Paer1 strain showed diffuse adhesion in the S. nigra-reactive region at the gel origin. In conclusion, an overlay adhesion assay was developed that identified slow-migrating sialylated glycoprotein species in human tears preferentially bound by P. aeruginosa ocular strains, and S. nigra lectin seemed to enhance the interaction. The study provides a basis for direct investigation of bacterial adhesion to glycoproteins with an apparent migration >200 kDa in tear fluid.

Migration of fallout radiocaesium in a grassland soil from 1986 to 2001: Part II: Evaluation of the activity–depth profiles by transport models

The vertical migration of 134Cs, deposited by the Chernobyl fallout (1986), and 137Cs, deposited by the Chernobyl and the global fallout, in the soil of an undisturbed Bavarian grassland in Germany was investigated from 1986 to 2001. The activity–depth profiles of both isotopes at ten sampling dates were evaluated by the classical convection–dispersion equation and a random walk particle model. In both models, the apparent migration velocity v and the apparent dispersion coefficient D were assumed to be independent of time. However, optimized values of v and D were significantly different for the different locations sampled at different times. If nevertheless constant values of v and D were used, the simulated activity densities per soil layer were out of the range of the spatial variability of the observed activity densities determined in 2001. It is concluded that without further simultaneous investigations e.g. on bioturbation at the study site, migration parameters of radiocaesium determined by classical transport models based on convection and dispersion during the first years after the deposition of the activity cannot be used for predictive purposes.

Paleomagnetism of Vendian rocks in the southwest of the Siberian Platform

[1] Presented in this paper are paleomagnetic data for the Vendian sedimentary rocks of the southwestern region of the Siberian Platform, obtained during the study of the reference rock sequences of the Central and Biryusa areas of the Sayan region and of the Yenisei mountain range in the lower reaches of the Angara River and its tributaries. This study proved the wide development of metachronous pre- and synfolding magnetization components which originated after the accumulation of the sedimentary rock sequences, yet, obviously not later than the Early Cambrian. All of the study rocks of the NemakitDaldynian age show two clearly distinguished paleomagnetic trends which seem to have formed during or soon after the accumulation of the rocks. Earlier, we got similar results for the Late Vendian rocks of the Southwest Baikal and East Sayan regions and also for the transitional Vendian-Lower Cambrian rock sequences of the Siberian Platform. This allowed us to infer the anomalous behavior of the geomagnetic field at the end of the Vendian to the beginning of the Lower Cambrian. The results obtained in the study reported here prove the actual basis of this hypothesis. During our study of the older Ediacarian and Ediacarian-Nemakit-Daldynian rocks, we managed to distinguish stable high-temperature magnetization components, obviously reflecting the trend of the geomagnetic field that existed during the accumulation of these rocks. The paleomagnetic poles corresponding to these components allowed us to reconstruct the late Vendian trend of the apparent migration of the pole and evaluate the character of the Siberian Platform movements during that time, which allowed us to chose the polarity for the Riphean paleomagnetic trends of Siberia. INDEX TERMS: 1520 Geomagnetism and Paleomagnetism: Magnetostratigraphy; 1525

Apparent migration of tremor source synchronized with the change in the tremor amplitude observed at Aso volcano, Japan

At Aso volcano, Kyushu, Japan, several different types of volcanic tremor have been observed for many years. One of them is the continuous tremor, the ground vibration which has dominant frequency between 3 and 10 Hz and has approximately constant amplitudes without any clear beginning and ending. We observed the continuous tremor at Aso using short period seismometer arrays for 3 days in 1999. We locate the source of the continuous tremor by seismic array data processing. We use the semblance coefficients in order to estimate the arrival azimuth and apparent slowness by grid search. The epicenters of the continuous tremor are located around the currently active crater, and the source depths are likely to be shallower than 600 m. We find that the estimated epicenter clearly migrates synchronized with the change in the tremor amplitude. The migration often occurs periodically with a period of about 80 s, but aperiodic occurrence of the migration is also often seen. In both cases, the epicenter is located southeastward (northwestward) when the amplitude is larger (smaller). We propose that there are two or more independent tremor sources with fixed locations, and that their amplitudes modulate either aperiodically or periodically with periods nearly 80 s. The tremor signals from those sources are mixed at the arrays, and the estimated epicenter parameters vary according to which signal dominates the seismograms. The simplest model is that there are two point sources, one at west and the other at south of the crater (we call the two sources as “NW source” and “SE source”, respectively), and the amplitude of the SE source changes with time. Consequently, the SE source dominates the seismogram when the observed amplitude is larger, whereas the NW source dominates when the amplitude is smaller. We generate synthetic seismograms, and apply the location technique to them to verify the validity of the two point source model and to search the locations of two sources which can explain the observed synchronization between the amplitude and the apparent epicenter location. We find that the distance between the two sources needs to be more than 400 m to agree with the observation. We also analyze the seismic array data observed in 2001, and infer that the NW source in 1999 may be identical to the tremor source of the 2001 data.

Shape of Moving Grain Boundary and its Influence on Grain Boundary Motion in Zinc

The migration of individual special [ ] 0 1 10 tilt grain boundary (GB) with Σ =15 and misorientation angle 29° in Zn bicrystal have been investigated. The stationary shape of migrating GB has been studied and the migration rate has been measured by optical microscopy in situ between 558 and 683 K using polarized light. In certain experimental runs the migrating GB is faceted and moves thermally activated. Its kinetics follows the Arrhenius type dependence despite the fact that shape of moving GB depends on temperature. After detachment from impurity cloud the [ ] 0 1 10 tilt GB migrates activationless in the temperature interval 618÷683 K. The detachment temperature is 618 K. The non-physically high value of the apparent migration activation enthalpy can appear due to the change of GB shape from faceted to smooth and back.

Influence of faceting-roughening on triple-junction migration in zinc

½� tilt grain boundaries (GBs) with misorientation angles h of 43° ,3 7° and 6°. The stationary shape of the migrating triple junction was studied, and the migration rate was measured in-situ between 670 and 688 K using polarized light. In some experimental runs, a facet was formed on the h ¼ 37° 10 1 ½� tilt GB. This facet was parallel to the close-packed plane in the constrained coincidence site lattice (CCSL). The length of this facet decreases with increasing temperature and becomes zero at 688 K. The temperature dependence of the facet length is better described by the meanfield Andreev approximation than by the solid-on-solid model. The step energy estimated in the framework of the Bonzel approximation is about 0.1 eV/atom. In other experimental runs, the h ¼ 37° 10 1 ½� tilt GB did not facet and remained rough in the same temperature interval. This fact allowed us to compare the stationary migration of the same TJ with faceted and rough GBs. A TJ formed by faceted GBs migrates one to two orders of magnitude more slowly in comparison with a rough TJ. An unrealistically high value of the apparent migration activation enthalpy of faceted TJs can appear due to the changing geometry of faceted GBs, similar to the case of migration of faceted twin tips.

Biology and functional morphology of a new species of endolithic Bryopa (Bivalvia: Anomalodesmata: Clavagelloidea) from Japan and a comparison with fossil species of Stirpulina and other Clavagellidae

Abstract. A new species of Clavagellidae, Bryopa aligamenta, from Okinawa, Japan, is described. The species is endolithic in living corals, with the left valve cemented to the crypt wall, as in all clavagellids. The free right valve exhibits an unusual growth pattern, with commarginal lines seemingly arising from the posterior valve margin and extending towards the anterior. This results from: (i) progressive anterior erosion of the umbones, probably as a consequence of the boring process; (ii) the apparent migration posteriorly, as the umbones are eroded, of the dorso‐ventral growth axis of the shell; and (iii) enhanced posterior inter‐commarginal growth. Unlike other clavagellid genera and species, however, there is no discernible primary ligament, at least in the adult. It is possible, however, that if a juvenile ligament were present (as in B. lata), it too would be lost as a consequence of antero‐dorsal erosion during boring. To retain valve alignment in the absence of a primary ligament, and possibly upon reaching an adult size, the mantle lays down alternating layers of calcium carbonate and proteinaceous periostracum onto the interior surface of the shell to thicken it, most noticeably marginally and, especially, posteriorly. The two valves are united dorsally, therefore, by thin layers of periostracum that probably exert a minimal opening force. B. aligamenta is, however, further characterised by large adductor, pallial, and siphonal retractor muscles so that the entire animal is encased tightly within an internally strengthened shell within a crypt. Movement must be minimal, blood being pumped into pallial haemocoels to push open the valves and extend the siphons. Despite a suggestion to the contrary, Bryopa is retained in the Clavagellidae, its unusual growth processes resulting from an endolithic life style within living corals.The fossil clavagellid Stirpulina bacillus, from the Pliocene/Pleistocene of Palermo, Sicily, Italy, was, unlike Bryopa aligamenta and other clavagellids, endobenthic, with a long adventitious tube and anterior watering pot superficially similar to species of Penicillidae, another family of the Clavagelloidea. Furthermore, as in all clavagellids only the left valve is fused into the fabric of the tube, the right being free within it. In all penicillids, both valves are fused into the fabric of their tubes. The watering pots of the fossil S. coronata, S. vicentina, and S. bacillus, moreover, are formed in a different manner to that of penicillids, by progressive encasement of the right valve inside the tube. In penicillids, the tube is secreted in a single event from the general mantle surface and the incorporation of both valves into its fabric. The constituent genera of the Clavagellidae thus constitute an example of parallel evolution with members of the Penicillidae.

Component Loosening in Total Hip Arthroplasty

Aseptic loosening in total hip arthroplasty remains a significant barrier to long-term implant survival. Improvements in surgical technique, designs, and biomaterials over the past three decades have improved loosening rates from an initial 30 to 40% at 10 years to present rates of 3% (femur) and less than 5% (acetabulum) at 10 years. Refinement of cement technique has made noted improvements in survivability of femoral cemented stems but little difference in cemented acetabular components. Long-term outcome of well-cemented femoral stems has been an established benchmark, but is rivaled, and in some cases surpassed, by the success of cementless designs in fixation. Recognition of circumstances that may accelerate the wear process, thus facilitating progressive lysis and eventual loosening, requires a keen consideration of materials, implant orientation, patient activity, and adequate clinical observation. Radiolucency is variable and provides evidence of potential loosening. Pain in the groin region or anterior thigh aggravated with weight bearing remains the most reliable clinical indicator. Change in component position or apparent migration from one consistent radiographic study to another signifies definitive evidence of loosening.

Real-time monitoring of a digestive tract marker to reduce adverse effects of moving organs at risk (OAR) in radiotherapy for thoracic and abdominal tumors

To evaluate the feasibility of real-time monitoring of a fiducial marker in/near the digestive tract and to analyze the motion of organs at risk to determine a reasonable internal margin. We developed two methods to insert a fiducial marker into/near the digestive tract adjacent to the target volume. One method involves an intraoperative insertion technique, and the other involves endoscopic insertion into the submucosal layer of the normal digestive tract. A fluoroscopic real-time tumor-tracking radiotherapy system was used to monitor the marker. Fourteen markers (2 in the mediastinum and 12 in the abdomen) were implanted intraoperatively in 14 patients with no apparent migration. Seventeen of 20 markers (13/14 in the esophagus, 1/2 in the stomach, and 3/4 in the duodenum) in 18 patients were implanted using endoscopy without dropping. No symptomatic adverse effects related to insertion were observed. The mean/standard deviation of the range of motion of the esophagus was 3.5/1.8, 8.3/3.8, and 4.0/2.6 mm for lateral, craniocaudal and anteroposterior directions, respectively, in patients with intrafractional tumor motion less than 1.0 cm. Both intraoperative and endoscopic insertions of a fiducial marker into/near the digestive tract for monitoring of organs at risk were feasible. The margin for internal motion can be individualized using this system.