BACKGROUND

The mechanical property of stiffness may be important to investigating how lateral ankle ligament injury affects the behavior of the viscoelastic properties of the ankle complex. A better understanding of injury effects on tissue elastic characteristics in relation to joint laxity could be obtained from cadaveric study.

OBJECTIVE

To biomechanically determine the laxity and stiffness characteristics of the cadaver ankle complex before and after simulated injury to the anterior talofibular ligament (ATFL) and calcaneofibular ligament (CFL) during anterior drawer and inversion loading.

METHODS

Cross-sectional study.

METHODS

University research laboratory.

METHODS

Seven fresh-frozen cadaver ankle specimens.

METHODS

All ankles underwent loading before and after simulated lateral ankle injury using an ankle arthrometer.

METHODS

The dependent variables were anterior displacement, anterior end-range stiffness, inversion rotation, and inversion end-range stiffness.

RESULTS

Isolated ATFL and combined ATFL and CFL sectioning resulted in increased anterior displacement but not end-range stiffness when compared with the intact ankle. With inversion loading, combined ATFL and CFL sectioning resulted in increased range of motion and decreased end-range stiffness when compared with the intact and ATFL-sectioned ankles.

CONCLUSIONS

The absence of change in anterior end-range stiffness between the intact and ligament-deficient ankles indicated bony and other soft tissues functioned to maintain stiffness after pathologic joint displacement, whereas inversion loading of the CFL-deficient ankle after pathologic joint displacement indicated the ankle complex was less stiff when supported only by the secondary joint structures.

BACKGROUND

Quinpirole (QNP), a D2/D3 dopaminergic receptor agonist, was found to elicit an apparently antieconomical drinking behavior called contrafreeloading (CFL). The perseverative operant responding observed may represent a compulsive-like behavior prompted by sensitization to the effects of QNP.

OBJECTIVE

In the present study, we investigated the effect of different response costs on instrumental behavior and CFL in rats repeatedly treated with QNP (0.5 mg/kg i.p.). Moreover, we studied the consummatory components of ingestive behavior in no-choice paradigms and the role of learned operant conditioning in free drinking.

METHODS

In experiment 1, rats were trained to perform under three different fixed ratio schedules of reinforcement (FR1, FR3, and FR10) and were given a choice between operant and free access to water. In experiment 2, rats were divided into four groups, each one resembling experiment 1 in one or more features, with no choice available and water consumption measured at an interval of 0-60 min.

RESULTS

(a) Increasing FR significantly reduced CFL % in saline -- but not in QNP-injected groups; (b) under free-drinking conditions, QNP caused a progressive hypodipsic effect which was, however, contrasted by maintaining cues formerly contingent on operant access to water; and (c) under CFL conditions QNP-treated rats drank more than under free access conditions.

CONCLUSIONS

QNP confers rigidity in responding for water, impeding adaptation to different contingencies for access to the resource. In QNP-treated rats, CFL behavior appears adaptive as far as it allows animals to partially circumvent the hypodipsic effect of the drug.

Alligator hindlimbs show high torsional loads during terrestrial locomotion, in sharp contrast to the bending or axial compressive loads that predominate in animals that use parasagittal limb movements. The present study integrates new data on hindlimb muscle function with previously obtained data on hindlimb kinematics, motor patterns, ground reaction forces and bone strain in order to (1) assess mechanisms underlying limb bone torsion during non-parasagittal locomotion in alligators and (2) improve understanding of hindlimb dynamics during terrestrial locomotion. Three dynamic stance phase periods were recognized: limb-loading, support-and-propulsion, and limb-unloading phases. Shear stresses due to torsion were maximized during the limb-loading phase, during which the ground reaction force (GRF) and caudofemoralis (CFL) muscles generated opposing moments about the femur. Hindlimb retraction during the subsequent stance-and-propulsion phase involves substantial medial rotation of the femur, powered largely by coordinated action of the GRF and CFL. Several muscles that actively shorten to flex and extend limb joints during stance phase in sprawling and erect quadrupeds act in isometric or even eccentric contraction in alligators, stabilizing the knee and ankle during the support-and-propulsion phase. Motor patterns in alligators reveal the presence of local and temporal segregation of muscle functions during locomotion with muscles that lie side by side dedicated to performing different functions and only one of 16 muscles showing clear bursts of activity during both stance and swing phases. Data from alligators add to other recent discoveries that homologous muscles across quadrupeds often do not move joints the same way as is commonly assumed. Although alligators are commonly considered models for early semi-erect tetrapod locomotion, many aspects of hindlimb kinematics, muscle activity patterns, and femoral loading patterns in alligators appear to be derived in alligators rather than reflecting an ancestral semi-erect condition.

Although bone bruises have been well described in the knee joint, little is known about their presence in the ankle joint. The present study attempted to document the association of bone bruises with lateral ankle sprains. Magnetic resonance (MR) images were obtained from 60 consecutive patients with lateral ankle sprains between April 1994 and June 1995. There were 29 men and 31 women, aged on average 25 years (range 12-68 years). All of the patients presented within 3 weeks of the sprain. MRI examinations were done within 3 weeks of the injury in 15, after 3-6 weeks in 21, and after 6-8 weeks in 24 cases. There were 28 first-time sprains, while 32 patients had suffered one or more sprains before the most recent one. Plain radiographs showed no evidence of osseous abnormality. Following the conventional MRI examination, magnetic resonance arthrography (MRA) was done by injecting 2 mM of gadolinium diethylene triamine penta-acetic acid (DTPA) into the joint under fluoroscopic control, and the same images were obtained again to search for ligamentous lesions. A total of 11 bone bruises were detected in 10 ankles. In this group of patients, there were 5 men and 5 women aged on average 27 years (range 12-50 years). Four MRI examinations were done within 3 weeks, while six were done 3-6 weeks after the injury. One ankle which had suffered one previous sprain and complete ruptures of anterior talofibular ligament (ATFL) and calcaneofibular ligament (CFL) had two lesions (talus and navicula). In another recurrent case with complete ATFL and CFL ruptures, the lesion was found in the calcaneus. The remaining eight lesions were in the talus in eight ankles. The ligamentous lesions in these ankles included three complete ATFL and CFL ruptures, and four isolated ATFL ruptures; in one ankle there were no ligamentous lesions. The location of talar bruises was medial in six and lateral in three ankles. The incidence of bone bruises associated with isolated ATFL lesions was 16% (4/25). With combined ATFL and CFL lesions the incidence was 50% (5/10). The incidence of ankles with bone bruises and first-time and recurrent sprains was 7% (2/28) and 25% (8/32), respectively. The occurrence of bone bruises should be kept in mind following ankle sprains. Their clinical significance in the long term remains to be determined.

Structural determinants underlaying the pH-dependent dimer-tetramer transition of Diocleinae lectins were investigated from the structures of Cratylia floribunda seed lectin crystallized in conditions where it exist as a dimer (pH 4.6) or as a tetramer (pH 8.5). The acidic (aCFL) and the basic (bCFL) tetramers superimpose with overall r.m.s.d. of 0.53 A, though interdimer contacts are drastically reduced in aCFL, and the r.m.s.d. for the superposition of the 117-120 loops of aCFL vs. the bCFL tetramer is 1.29 A. Our data support the view that His51 plays a role in determining the conformation of the central cavity loops and that interdimer contacts involving ordered loop residues stabilize the canonical, pH-dependent tetramer. In the bCFL tetramer, hydrogen bonds between Asn118 and Thr120 of monomers A and D and residues Ser66, Ser108, Ser110, and Thr49 of the opposite monomer stabilize the canonical, pH-dependent tetrameric lectin structure. In CFL, Asn131 makes intradimer contacts with Asn122 and Ala123. In comparison, His131 in Dioclea grandiflora lectin establishes a network of interdimer interactions bridging the four central loops of the pH-independent tetramer. Our data provide new insights into the participation of specific amino acid residues in the mechanism of the quaternary association of Diocleinae lectins.

BACKGROUND

Periplocin is used for treatment of rheumatoid arthritis, reinforcement of bones and tendons, palpitations or shortness of breath and lower extremity edema in traditional medicine. Our previous findings suggested that periplocin could inhibit the growth of lung cancer both in vitro and in vivo. But the biological processes and molecular pathways by which periplocin induces these beneficial effects remain largely undefined.

METHODS

To explore the molecular mechanisms of periplocin involved in anti-cancer activity, in the present study the protein profile changes of human lung cancer cell lines A549 in response to periplocin treatment were investigated using the proteomics approaches (2-DE combined with MS/MS). Western blot was employed to verify the changed proteins. Interactions between changed proteins were analyzed by STRING.

RESULTS

29 down-regulated protein species named GTP-binding nuclear protein Ran (RAN), Rho GDP-dissociation inhibitor 1 (ARHGDIA), eukaryotic translation initiation factor 5A-1 (EIF5A) and Profilin-1(PFN1), and 10 up-regulated protein species named Heat shock cognate 71 kDa protein (HSPA8),10 kDa heat shock protein (HSPE1), and Cofilin-1(CFL-1) were identified. Among them, GTP-binding nuclear protein Ran (RAN) and Rho GDP-dissociation inhibitor 1 (ARHGDIA) were the most significantly changed (over tenfold). The proteasome subunit beta type-6 (PSMB6), ATP synthase ecto-α-subunit (ATP5A1), Aldehyde dehydrogenase 1 (ALDH1) and EIF5A were verified by immunoblot assays to be dramatically down-regulated. By STRING bioinformatics analysis revealing interactions and signaling networks it became apparent that the proteins changed they are primarily involved in transcription and proteolysis.

CONCLUSIONS

Periplocin inhibited growth of lung cancer by down-regulating proteins, such as ATP5A1, EIF5A, ALDH1 and PSMB6. These findings may improve our understanding of the molecular mechanisms underlying the anti-cancer effects of periplocin on lung cancer cells.

Artificial lighting allows humans to be active at night, but has many unintended consequences, including interference with ecological processes, disruption of circadian rhythms and increased exposure to insect vectors of diseases. Although ultraviolet and blue light are usually most attractive to arthropods, degree of attraction varies among orders. With a focus on future indoor lighting applications, we manipulated the spectrum of white lamps to investigate the influence of spectral composition on number of arthropods attracted. We compared numbers of arthropods captured at three customizable light-emitting diode (LED) lamps (3510, 2704 and 2728 K), two commercial LED lamps (2700 K), two commercial compact fluorescent lamps (CFLs; 2700 K) and a control. We configured the three custom LEDs to minimize invertebrate attraction based on published attraction curves for honeybees and moths. Lamps were placed with pan traps at an urban and two rural study sites in Los Angeles, California. For all invertebrate orders combined, our custom LED configurations were less attractive than the commercial LED lamps or CFLs of similar colour temperatures. Thus, adjusting spectral composition of white light to minimize attracting nocturnal arthropods is feasible; not all lights with the same colour temperature are equally attractive to arthropods.

The compensation of spontaneous nystagmus and head deviation following chemical unilateral labyrinthectomy (UL) induced by arsanilate was delayed compared with surgical UL. Surgical UL produced two phases of significant asymmetry of cFos-like (cFL) protein expression between the bilateral medial vestibular nuclei, with more expression in the contralateral medial vestibular nuclei to the injured side than in the ipsilateral medial vestibular nuclei 2 h after UL; the pattern reversed after 6 h and expression disappeared after 72 h. Chemical UL produced three phases of asymmetric expression, with more cFL protein expression in the contralateral medial vestibular nuclei than in the ipsilateral medial vestibular nuclei 6 h after UL and a reversed pattern after 12 h. Asymmetric expression 72 h after UL followed increased expression in the contralateral medial vestibular nuclei. These results suggest that the course of vestibular compensation and the temporal expression of cFL protein in the medial vestibular nuclei following UL differed between surgical and chemical labyrinthectomy.

The recent development in immune checkpoint inhibitors and chimeric antigen receptor (CAR) T-cells in the treatment of cancer has not only demonstrated the potency of utilizing T-cell reactivity for cancer therapy, but has also highlighted the need for developing new approaches to discover targets suitable for such novel therapeutics. Here we analyzed the immunopeptidomes of six HLA-A2-positive triple negative breast cancer (TNBC) samples by nano-ultra performance liquid chromatography tandem mass spectrometry (nUPLC-MS2 ). Immunopeptidomic profiling identified a total of 19 675 peptides from tumor and adjacent normal tissue and 130 of the peptides were found to have higher abundance in tumor than in normal tissues. To determine potential therapeutic target proteins, we calculated the average tumor-associated cohort coverage (aTaCC) that represents the percentage coverage of each protein in this cohort by peptides that had higher tumoral abundance. Cofilin-1 (CFL-1), interleukin-32 (IL-32), proliferating cell nuclear antigen (PCNA), syntenin-1 (SDCBP), and ribophorin-2 (RPN-2) were found to have the highest aTaCC scores. We propose that these antigens could be evaluated further for their potential as targets in breast cancer immunotherapy and the small cohort immunopeptidomics analysis technique could be used in a wide spectrum of target discovery. Data are available via ProteomeXchange with identifier PXD009738.

Injuries to the lateral ligaments of the ankle are common in medical practice. The most commonly injured ligaments are the anterior talofibular (ATFL) and calcaneofibular (CFL) ligaments. When undertaking MRI evaluation of ankle injuries it is important to understand the normal dimensions, appearance and variations of these ligaments. Twenty-eight consecutive patients referred for MRI of the ankle underwent bilateral scanning. The thickness of normal and abnormal ATFL and CFL was determined. The mean thickness of the ATFL was 2.19 +/- 0.6 mm and the CFL measured 2.13 +/- 0.5 mm. One normal ankle had an extremely thin ATFL (0.8 mm) with an otherwise normal appearance, whereas two ankles had an ATFL with a high attachment, both of which were deemed to be normal variants. Nineteen per cent of normal CFLs were noted to consist of a lateral hypointense band with a medial isointense medial band. Two variations of normal ATFL, one normal variant CFL and a measurement of the normal thickness of the ATFL and CFL have been presented in this paper. These variations have not been described previously by other authors. It is envisaged that these findings will assist in the MRI assessment of the lateral ankle ligaments.

Near-infrared spectroscopy (NIRS) monitors changes in the regional cerebral oxygenation (rSO) and has been used to study cerebral physiologic functions in normal states and during epileptic seizures. Yet, the limitations and pitfalls of the technique are not fully understood. The authors evaluated NIRS changes over the frontal lobes during language tasks known to be associated with the integrity of the dominant frontal lobe in 17 normal adults (handedness: 14 right, 3 left). Recording protocol involved a baseline (3 minutes) with the subject relaxed and thinking of a blue sky and a second baseline during voluntary mouth movements mimicking speech. Two standardized neuropsychological word-generation tasks (controlled word-association tests: CFL and Animals) were then administered (4 minutes total) followed again by the two baseline procedures. Mouth movement without verbalization increased rSO values in excess of 2 SD of baseline fluctuations in 70% of the subjects. A t-test comparison of these baseline measurements was statistically significant (P < 0.0001). A general linear model repeated-measures procedure was then used to statistically examine NIRS increments during the cognitive tasks above and beyond the contribution produced by mouth movements during the second baseline. Compared to the second baseline, rSO further increased significantly during the word generation tasks (left frontal F value = 21.4, P < 0.0001; right frontal F value = 15.2, P < 0.001), confirming the utility of the technique. There was no apparent difference related to handedness. These findings corroborate the usefulness of NIRS to demonstrate focal cerebral activation during an "executive" language task. However, interpretation of changes can be confounded by extracerebral factors such as mouth movement, a finding of particular relevance in NIRS clinical applications.

The equivalence of forms CFL and PRW of the Controlled Oral Word Association Test (COWAT; Benton, de Hamsher, & Sivan; 1994) was examined in samples of healthy college students. Both novel words and qualitative scores (e.g., clusters, switches) were examined using null hypothesis statistical testing (NHST) and inferential confidence intervals (Tryon, 2001). Study 1 used a within-subjects design (n = 66) to examine form equivalence in persons who completed versions CFL and PRW. No mean differences were found for any index, and only one (mean cluster size) differed when examining the standard deviations across forms. Inferential confidence intervals were constructed and Rg (maximum probable difference) values were small and, when compared to prior research, less than the standard error of measure associated with using a single form. In Study 2, we employed a between-subjects design (n = 208) and found that the use of each version generated comparable normative data and correlations among scores. These studies suggest that versions CFL and PRW are best viewed as alternate (rather than parallel) forms at this time; however, they are likely to produce comparable results for most purposes. We discuss the use of inferential confidence intervals to examine form equivalence and directions for future work.

Despite the importance of platelets in the formation of a thrombus, their transport in complex flows has not yet been studied in detail. In this paper we simulated red blood cells and platelets to explore their transport behaviour in aneurysmal geometries. We considered two aneurysms with different aspect ratios (AR = 1.0, 2.0) in the presence of fast and slow blood flows (Re = 10, 100), and examined the distributions of the cells. Low velocities in the parent vessel resulted in a large stagnation zone inside the cavity, leaving the initial distribution almost unchanged. In fast flows, an influx of platelets into the aneurysm was observed, leading to an elevated concentration. The connection of the platelet-rich cell-free layer (CFL) with the outer regions of the recirculation zones leads to their increased platelet concentration. These platelet-enhanced recirculation zones produced a diverse distribution of cells inside the aneurysm, for the different aspect ratios. A thin red blood CFL that was occupied by platelets was observed on the top of the wide-necked aneurysm, whereas a high-haematocrit region very close to the vessel wall was present in the narrow-necked case. The simulations revealed that non-trivial distributions of red blood cells and platelets are possible inside aneurysmal geometries, giving rise to several hypotheses on the formation of a thrombus, as well as to the wall weakening and the possible rupture of an aneurysm.

In small vessels blood is usually treated as a Newtonian fluid down to diameters of ~200 μm. We investigate the flow of red blood cell (RBC) suspensions driven through small tubes (diameters 10-150 μm) in the range marking the transition from arterioles and venules to the largest capillary vessels. The results of the simulations combined with previous simulations of uniform shear flow and experimental data show that for diameters less than ~100 μm the suspension's stress cannot be described as a continuum, even a heterogeneous one. We employ the dissipative particle dynamics (DPD) model, which has been successfully used to predict human blood bulk viscosity in homogeneous shear flow. In tube flow the cross-stream stress gradient induces an inhomogeneous distribution of RBCs featuring a centreline cell density peak, and a cell-free layer (CFL) next to the wall. For a neutrally buoyant suspension the imposed linear shear-stress distribution together with the differentiable velocity distribution allow the calculation of the local viscosity across the tube section. The viscosity across the section as a function of the strain rate is found to be essentially independent of tube size for the larger diameters and is determined by the local haematocrit (H) and shear rate. Other RBC properties such as asphericity, deformation, and cell-flow orientation exhibit similar dependence for the larger tube diameters. As the tube size decreases below ~100 μm in diameter, the viscosity in the central region departs from the large-tube similarity function of the shear rate, since H increases significantly towards the centreline. The dependence of shear stress on tube size, in addition to the expected local shear rate and local haematocrit, implies that blood flow in small tubes cannot be described as a heterogeneous continuum. Based on the analysis of the DPD simulations and on available experimental results, we propose a simple velocity-slip model that can be used in conjunction with continuum-based simulations.

The Cfl xyn11A gene, encoding the endo-1,4-beta-xylanase Cfl Xyn11A from Cellulomonas flavigena, was isolated from a genomic DNA library. The open reading frame of the Cfl xyn11A gene was 999 base pairs long and encoded a polypeptide (Cfl Xyn11A) of 332 amino acids with a calculated molecular mass of 35,110Da. The Cfl xyn11A gene was expressed in Escherichia coli and the recombinant enzyme, with an estimated molecular weight of 31kDa was purified and xylanase activity was measured. Cfl Xyn11A showed optimal activity at pH 6.5 and 55 degrees C. The enzyme demonstrated moderate thermal stability as Cfl Xyn11A maintained 50% of its activity when incubated at 55 degrees C for 1h or at 45 degrees C for 6h. This is the first report describing the cloning, expression and functional characterization of an endo-1,4-beta-xylanase-encoding gene from C. flavigena. Cfl Xyn11A may be suitable for industrial applications in the food and feed industries, or in the pre-treatment of lignocellulosic biomass required to improve the yields of fermentable sugars for bioethanol production.

Photoexcited acetophenone can catalyze the fluorination of unactivated C(sp(3))-H groups. While acetophenone, a colorless oil, only has a trace amount of absorption in the visible light region, its photoexcitation can be achieved by irradiation with light generated by a household compact fluorescent lamp (CFL). This operational simple method provides improved substrate scope for the direct incorporation of a fluorine atom into simple organic molecules. CFL-irradiation can also be used to promote certain classic UV-promoted photoreactions of colorless monoarylketones and enones/enals.

BACKGROUND

Sentence context increases reading speed relative to reading unrelated words. Previous studies of normal peripheral retina and in patients with central field loss (CFL) have come to different conclusions regarding the benefits of sentence context for reading in peripheral retina. Studies of normal peripheral vision presented the text to inferior visual field; it is presumed that most of the patients fixated using retina lateral to their scotoma. The goal of the current study was to determine whether the location of the text on the retina interacts with the usefulness of sentence context.

METHODS

Normally sighted subjects read sentences and random lists of words presented at the fovea and at 50 to the left of and 50 inferior to fixation in visual field space. Texts were presented using rapid serial visual presentation (RSVP).

RESULTS

The ratio of reading rates for sentences to random words (context gain) was the same in the inferior field (2.7 +/- 0.20) and at the fovea (2.6 +/- 0.26); context gain was greater in the left field (7.2 +/- 1.22).

CONCLUSIONS

Sentence context increases reading speed regardless of the position of the text on the retina. Reading rates in peripheral retina are not decreased because of an inability to use sentence context.

A model of low-phosphate, vitamin D-deficient rachitic rats was used to compare the effects of 1 alpha(OH)D3, 1,25(OH)2D3, and 24,25(OH)2D3 on cartilage and bone. The rats were maintained for 3 weeks on a high-calcium, low-phosphate, vitamin D-deficient diet, during which period they developed severe rickets. The rachitic rats were injected for 2 or 3 consecutive days with a physiologic dose of either metabolite. Other littermates were given a single dose of 50,000 IU of cholecalciferol in combination with a normal diet. Samples of cartilage fluid (Cfl) and of blood were removed prior to sacrifice for biochemical studies of some parameters of calcification. These parameters were correlated with the results of light and electron microscopic studies of the growth plate cartilage and bone. Treatment with 1 alpha (OH)D3 or with 1,25(OH)2D3, in spite of increasing Ca and P levels in the Cfl, induced only partial healing of the rickets. In contrast, 24,25(OH)2D3 or vitamin D with a normal diet resulted in complete morphologic and biochemical healing of the rickets. Transmission electron microscopic (TEM) studies have shown partial mineralization of the wide hypertrophic zone of the growth plate following treatment with 1 alpha(OH)D3 or with 1,25(OH)2D3. Mineralization was more complete with 24,25(OH)2D3 treatment. The results of this study emphasize the importance of 24,25(OH)2D3 for normal endochondral bone formation and mineralization.

We present new methods that enable the fabrication of multiscale, multicomponent protein-patterned surfaces and multiscale topologically structured surfaces by exploiting the merits of two well-established techniques: capillary force lithography (CFL) and microscope projection photolithography (MPP) based on a protein-friendly photoresist. We further demonstrate that, when hierarchically organized micro- and nanostructures were used as a cell culture platform, human colon cancer cells (cell line SW480) preferentially adhere and migrate onto the area with nanoscale topography over the one with microscale topography. These methods will provide many exciting opportunities for the study of cellular responses to multiscale physicochemical cues.

The ligamentous spinal column buckles under compressive loads of even less than 100N. Experimental results showed that under the follower load constraint, the ligamentous lumbar spine can sustain large compressive loads without buckling, while at the same time maintaining its flexibility reasonably well. The purpose of this study was to investigate the feasibility of follower loads produced by spinal muscles in the lumbar spine in a quiet standing posture. A three-dimensional static model of the lumbar spine incorporating 232 back muscles was developed and utilized to perform the optimization analysis in order to find the muscle forces, and compressive follower loads (CFLs) along optimum follower load paths (FLPs). The effect of increasing external loads on CFLs was also investigated. An optimum solution was found which is feasible for muscle forces producing minimum CFLs along the FLP located 11 mm posterior to the curve connecting the geometrical centers of the vertebral bodies. Activation of 30 muscles was found to create CFLs with zero joint moments in all intervertebral joints. CFLs increased with increasing external loads including FLP deviations from the optimum location. Our results demonstrate that spinal muscles can create CFLs in the lumbar spine in a neutral standing posture in vivo to sustain stability. Therefore, its application in experimental and numerical studies concerning loading conditions seems to be suitable for the attainment of realistic results.

OBJECTIVE

An anatomical study was performed to assess the feasibility of arthroscopic visualization of the lateral ligaments of the ankle.

METHODS

The fibular, talar and calcanear insertions of the anterior talofibular ligament (ATFL) and calcaneofibular ligament (CFL) were identified by standard arthroscopy portals. After dissection of the ATFL and CFL, bone tunnels were created at the estimated centres of their footprints. Dissection was then performed to identify the footprints and their position in relation to bony landmarks. The distance from the real centre of the footprint to the corresponding tunnel entrance was measured.

RESULTS

Fourteen fresh frozen ankles were included. The ATFL and CFL were identified in all cases. The centre of the fibular ATFL footprint was found to be 16.1 ± 3.5 mm from the tip of the fibula, and the talar footprint was 18.4 ± 2.8 mm from the apex of the lateral talar process. The centre of the fibular CFL footprint was 4.2 ± 0.8 mm from the tip of the fibula, and the calcaneal footprint was 18.4 ± 2.5 mm from the fibular process of the calcaneum. The fibular tunnel was 2.9 ± 3 mm proximally from the centre of the ATFL fibular footprint, the talar tunnel was 4.4 ± 3.2 mm proximally from the centre of the talar footprint, and the calcaneal tunnel was 3.3 ± 2.8 mm too anterior from the CFL calcaneal footprint. No iatrogenic lesions were noted.

CONCLUSIONS

Arthroscopic identification of the ATFL, CFL and their corresponding footprints can be considered safe and reliable. Tunnels entrances, in preparation for arthroscopic ligament reconstruction, are precisely positioned. Arthroscopic anatomical ligament reconstruction is a feasible option.

We compare the predictive capability of two mathematical models for red blood cells (RBCs) focusing on blood flow in capillaries and arterioles. Both RBC models as well as their corresponding blood flows are based on the dissipative particle dynamics (DPD) method, a coarse-grained molecular dynamics approach. The first model employs a multiscale description of the RBC (MS-RBC), with its membrane represented by hundreds or even thousands of DPD-particles connected by springs into a triangular network in combination with out-of-plane elastic bending resistance. Extra dissipation within the network accounts for membrane viscosity, while the characteristic biconcave RBC shape is achieved by imposition of constraints for constant membrane area and constant cell volume. The second model is based on a low-dimensional description (LD-RBC) constructed as a closed torus-like ring of only 10 large DPD colloidal particles. They are connected into a ring by worm-like chain (WLC) springs combined with bending resistance. The LD-RBC model can be fitted to represent the entire range of nonlinear elastic deformations as measured by optical-tweezers for healthy and for infected RBCs in malaria. MS-RBCs suspensions model the dynamics and rheology of blood flow accurately for any vessel size but this approach is computationally expensive for vessel diameters above 100μm. Surprisingly, the much more economical suspensions of LD-RBCs also capture the blood flow dynamics and rheology accurately except for small-size vessels comparable to RBC diameter. In particular, the LD-RBC suspensions are shown to properly capture the experimental data for the apparent viscosity of blood and its cell-free layer (CFL) in tube flow. Taken together, these findings suggest a hierarchical approach in modeling blood flow in the arterial tree, whereby the MS-RBC model should be employed for capillaries and arterioles below 100μm, the LD-RBC model for arterioles, and the continuum description for arteries.

OBJECTIVE

To determine whether people with central visual field loss (CFL) show a smaller visual contribution to posture stabilization than people with normal vision and to determine the visual factors that predict the magnitude of visual stabilization in people with central visual field loss.

METHODS

Posture information was recorded in 19 subjects with CFL and in 20 subjects with normal vision. Data were collected as the subject stood in a dark environment and also as he or she viewed a stationary visual display. In both conditions, somatosensory feedback was concurrently altered. The central visual fields of the subjects with CFL were measured by static perimetry with the confocal scanning laser ophthalmoscope. Binocular visual acuity and contrast sensitivity were measured on all subjects using the ETDRS and Pelli-Robson charts, respectively. Image-displacement thresholds were measured in a subset of the subjects.

RESULTS

On average, subjects with central field loss showed a smaller visual contribution to posture stabilization than subjects with normal vision. The reduction in sway caused by visual stimuli was only 29% for the subjects with CFL compared to 41% for the subjects with normal vision. Displacement thresholds accounted for 45% of the variance in the visual stabilization magnitude of the subjects with CFL. No other visual factor significantly increased the coefficient of determination.

CONCLUSIONS

The visual self-motion cues generated by small body oscillations may be undetectable and, thus, unusable as cues to postural sway by people with central field loss.