Targeting damaged collagen for intra-articular delivery of therapeutics using collagen hybridizing peptides

The objective of this study was to investigate the potential of collagen hybridizing peptides (CHPs), which bind to denatured collagen, to extend the retention time of near-infrared fluorophores (NIRF) following intra-articular (IA) injection in rat knee joints. CHPs were synthesized with a NIRF conjugated to the N-terminus. Male Sprague-Dawley rats were assigned to one of four experimental groups: healthy, CHP; osteoarthritis (OA), CHP; healthy, scrambled-sequence CHP (sCHP), which has no collagen binding affinity; or OA, sCHP. Animals in the OA groups received an IA injection of monosodium iodoacetate to induce OA. All animals then received the corresponding CHP injection. Animals were imaged repeatedly over 2 weeks using an in vivo fluorescence imaging system. Joint components were isolated and imaged to determine CHP binding distribution. Safranin-O and Fast Green histological staining was performed to confirm the development of OA. CHPs were found to be retained within the joint following IA injection in both healthy and OA animals for the full study period. In contrast, sCHP signal was negligible by 24-48 h. CHP signal was significantly greater (p < 0.05) in OA joints when compared to healthy joints. At the 2-week end point, multiple joint components retained CHPs, including cartilage, meniscus, and synovium. CHPs dramatically extended the retention time of NIRFs following IA injection in healthy and OA knee joints by binding to multiple collagenous tissues in the joint. These results support the pursuit of further research to develop CHP based therapeutics for IA treatment of OA.

Extracellular matrix compression temporally regulates microvascular angiogenesis

Mechanical cues influence tissue regeneration, and although vasculature is known to be mechanically sensitive, little is known about the effects of bulk extracellular matrix deformation on the nascent vessel networks found in healing tissues. Previously, we found that dynamic matrix compression in vivo potently regulated revascularization during bone tissue regeneration; however, whether matrix deformations directly regulate angiogenesis remained unknown. Here, we demonstrated that load initiation time, magnitude, and mode all regulate microvascular growth, as well as upstream angiogenic and mechanotransduction signaling pathways. Immediate load initiation inhibited angiogenesis and expression of early sprout tip cell selection genes, while delayed loading enhanced microvascular network formation and upstream signaling pathways. This research provides foundational understanding of how extracellular matrix mechanics regulate angiogenesis and has critical implications for clinical translation of new regenerative medicine therapies and physical rehabilitation strategies designed to enhance revascularization during tissue regeneration.

Individual and contextual predictors of retention in Special Olympics for youth with intellectual disability: who stays involved?

BACKGROUND

Despite the recognised benefits of sport, participation is often reported to be low for youth with intellectual disability (ID). The current study was the first to longitudinally examine sport retention in this population, a critical aspect of ensuring participation.

METHODS

Study participants were parents/caregivers of athletes with ID involved in community Special Olympics (SO), 11-22 years of age (N = 345). Participants completed an online survey in 2012 that included caregiver demographic and athlete intrapersonal, interpersonal and broader contextual variables. Retention rates for 2019 were determined using the SO provincial registration lists.

RESULTS

Of the 345 survey participants, 81.7% remained active athletes in 2019. Caregiver demographic and athlete intrapersonal factors were largely unrelated to retention. In contrast, retention was associated with the frequency and number of sports athletes participated in, the perceived psychosocial gains of SO involvement and the environmental supports that were available to facilitate participation; frequency of sport participation was the strongest predictor of remaining a registered athlete.

CONCLUSIONS

This study has implications for future initiatives aimed at increasing sport retention in a population that struggles to be engaged in sport. Efforts should focus on the athlete experience and sport-specific factors. Coaches and caregivers can foster positive experiences and play an important role in continued sport participation.

The quality of life of children with severe developmental disabilities

BACKGROUND

Research examining the quality of life (QoL) of children with severe developmental disabilities (SDD) is limited. The present study examines parent perceptions of child QoL in children with SDD compared with typically developing (TD) children and then examines predictors of QoL for the SDD group.

METHOD

Parents of 246 children with SDD (aged 4 to 19 years) and 210 TD children (aged 4 to 18 years) responded to an online survey. QoL was measured using a composite variable composed of the child's happiness, achievement of potential and friendship quality.

RESULTS

Children with DD had lower QoL ratings than TD children. In children with DD, higher QoL was related to younger age, higher adaptive skills, lower maladaptive behaviour, lower parent psychological distress and higher satisfaction with the child's education.

CONCLUSIONS

Interventions to promote positive outcomes for children with SDD should target both characteristics of the individual and the environment.

A systematic literature review of the physical and psychosocial correlates of Special Olympics participation among individuals with intellectual disability

BACKGROUND

Special Olympics (SO) is commonly cited to play an important role in the lives of individuals with intellectual disabilities (ID). The purpose of the current review was to (a) synthesise key findings regarding the physical, psychological/emotional, social and/or intellectual/cognitive correlates of SO participation for individuals with ID and (b) highlight limitations in the extant research as well as directions for future research.

METHOD

A systematic review of electronic databases was undertaken. A total of 46 articles were confirmed to meet study criteria. Quality assessments of included studies were conducted using checklists from the Scottish Intercollegiate Guidelines Network methodology checklists (SIGN 50; SIGN 2008).

RESULTS

There was a larger amount of support for physical, psychological/emotional and social outcomes as compared with cognitive/intellectual outcomes; however, many studies were confounded by measurement difficulties, sampling procedures and a lack of replicable methods, which hinder generalisation of results.

CONCLUSIONS

This review highlights the need for a continued critical focus on SO programme evaluation research with more rigorous and replicable methods.

Community participation of youth with intellectual disability and autism spectrum disorder

BACKGROUND

Community participation is associated with a range of positive developmental outcomes; however, the frequency, depth and resources associated with participation for youth with intellectual disability (ID) and autism spectrum disorder (ASD) are not well understood.

METHOD

Caregivers of 212 youth with ASD and ID and only ID, aged 11-22 years, completed an online survey. Comparisons were made of caregiver reports of diversity and frequency of participation, levels of participation involvement and related environmental barriers and supports.

RESULTS

The diversity and frequency of community participation of youth with ASD and ID approximated that of youth with ID only. Youth with ASD and ID were reported to be significantly less involved in the community activities in which they participated. Environmental features, and in particular, the social demands of community-based activities, were significant barriers to youths' participation.

CONCLUSIONS

The current study highlights individual and environmental factors amenable to intervention that may foster successful community participation among youth with ASD and ID.

Psychosocial correlates of psychiatric diagnoses and maladaptive behaviour in youth with severe developmental disability

BACKGROUND

We know little about the correlates of mental health problems in youth with severe and profound intellectual disability (ID), as most research includes these youth within larger samples that include greater proportions of mild and moderate disability. The purpose of the current study was to identify the child, family and psychosocial characteristics that were associated with the presence of psychiatric diagnoses and maladaptive behaviour in youth with severe ID.

METHODS

Participants were 141 parents of youth with severe or profound levels of ID, 4 to 18 years of age. The mean age of children was 11.04 years (SD = 3.38), with 68% male and 39% with autism spectrum disorder (ASD). Parents completed a primarily online survey of child and family characteristics, negative life events, family quality of life and their own mental health.

RESULTS

Logistic regression analyses revealed that youth with a psychiatric diagnosis had higher levels of adaptive behaviour and experienced more negative life events than youth without psychiatric diagnosis, while the presence of clinically significant maladaptive behaviour was related to higher levels of adaptive behaviour, parents' mental health problems and lower family quality of life. Child age, gender, ASD status and financial hardship were not related to either outcome variable.

CONCLUSIONS

Youth with severe and profound ID who experience psychosocial stressors are more likely reported to have mental health problems than youth without such stressors. It is likely that a combination of child and family based interventions, along with with policies that address larger systemic issues of social adversity, are needed to promote mental health and treat psychopathology when it arises.

Predictors of distress and well-being in parents of young children with developmental delays and disabilities: the importance of parent perceptions

BACKGROUND

Moving from family-centred to child-centred models of service delivery can be stressful for parents as their young children with developmental delays and disabilities transition into school. The purpose of this paper was to explore and compare predictors of both distress and well-being in parents during this transition period.

METHODS

A sample of 155 mothers of 113 boys and 42 girls participated in the study. The mean age of the children was 4.9 years and their diagnoses included autism spectrum disorder (52%); unspecified intellectual disability/developmental delay (26%); Down syndrome (12%); other genetic conditions (4%) and other diagnoses (6%). Participants completed surveys primarily online focusing on child characteristics, family resources, parent coping strategies, parental distress and positive gain.

RESULTS

Multiple regression analyses were conducted to determine predictors of parent reported distress and positive gain. Parent coping variables were the strongest predictors of both positive gain and parental distress, with reframing emerging as a predictor of positive gain and parent empowerment emerging as a predictor of both greater positive gain and lower parental distress.

CONCLUSIONS

The results of this study highlight not only the importance of including positive as well as negative outcomes in research with parents but also the importance of including parent characteristics such as coping strategies (e.g. reframing and empowerment/self-efficacy) as potential predictors of outcome in such studies.

A new sensor for measurement of dynamic contact stress in the hip

Various techniques exist for quantifying articular contact stress distributions, an important class of measurements in the field of orthopaedic biomechanics. In situations where the need for dynamic recording has been paramount, the approach of preference has involved thin-sheet multiplexed grid-array transducers. To date, these sensors have been used to study contact stresses in the knee, shoulder, ankle, wrist, and spinal facet joints. Until now, however, no such sensor had been available for the human hip joint due to difficulties posed by the deep, bi-curvilinear geometry of the acetabulum. We report here the design and development of a novel sensor capable of measuring dynamic contact stress in human cadaveric hip joints (maximum contact stress of 20 MPa and maximum sampling rate 100 readings/s). Particular emphasis is placed on issues concerning calibration, and on the effect of joint curvature on the sensor's performance. The active pressure-sensing regions of the sensors have the shape of a segment of an annulus with a 150-deg circumferential span, and employ a polar/circumferential "ring-and-spoke" sensel grid layout. There are two sensor sizes, having outside radii of 44 and 48 mm, respectively. The new design was evaluated in human cadaver hip joints using two methods. The stress magnitudes and spatial distribution measured by the sensor were compared to contact stresses measured by pressure sensitive film during static loading conditions that simulated heel strike during walking and stair climbing. Additionally, the forces obtained by spatial integration of the sensor contact stresses were compared to the forces measured by load cells during the static simulations and for loading applied by a dynamic hip simulator. Stress magnitudes and spatial distribution patterns obtained from the sensor versus from pressure sensitive film exhibited good agreement. The joint forces obtained during both static and dynamic loading were within ±10% and ±26%, respectively, of the forces measured by the load cells. These results provide confidence in the measurements obtained by the sensor. The new sensor's real-time output and dynamic measurement capabilities hold significant advantages over static measurements from pressure sensitive film.

Computed tomography arthrography with traction in the human hip for three-dimensional reconstruction of cartilage and the acetabular labrum

AIM

To develop and demonstrate the efficacy of a computed tomography arthrography (CTA) protocol for the hip that enables accurate three-dimensional reconstructions of cartilage and excellent visualization of the acetabular labrum.

MATERIALS AND METHODS

Ninety-three subjects were imaged (104 scans); 68 subjects with abnormal anatomy, 11 patients after periacetabular osteotomy surgery, and 25 subjects with normal anatomy. Fifteen to 25 ml of contrast agent diluted with lidocaine was injected using a lateral oblique approach. A Hare traction splint applied traction during CT. The association between traction force and intra-articular joint space was assessed qualitatively under fluoroscopy. Cartilage geometry was reconstructed from the CTA images for 30 subjects; the maximum joint space under traction was measured.

RESULTS

Using the Hare traction splint, the intra-articular space and boundaries of cartilage could be clearly delineated throughout the joint; the acetabular labrum was also visible. Dysplastic hips required less traction (∼5 kg) than normal and retroverted hips required (>10 kg) to separate the cartilage. An increase in traction force produced a corresponding widening of the intra-articular joint space. Under traction, the maximum width of the intra-articular joint space during CT ranged from 0.98-6.7 mm (2.46 ± 1.16 mm).

CONCLUSIONS

When applied to subjects with normal and abnormal hip anatomy, the CTA protocol presented yields clear delineation of the cartilage and the acetabular labrum. Use of a Hare traction splint provides a simple, cost-effective method to widen the intra-articular joint space during CT, and provides flexibility to vary the traction as required.

Multiscale mechanics of articular cartilage: potentials and challenges of coupling musculoskeletal, joint, and microscale computational models

Articular cartilage experiences significant mechanical loads during daily activities. Healthy cartilage provides the capacity for load bearing and regulates the mechanobiological processes for tissue development, maintenance, and repair. Experimental studies at multiple scales have provided a fundamental understanding of macroscopic mechanical function, evaluation of the micromechanical environment of chondrocytes, and the foundations for mechanobiological response. In addition, computational models of cartilage have offered a concise description of experimental data at many spatial levels under healthy and diseased conditions, and have served to generate hypotheses for the mechanical and biological function. Further, modeling and simulation provides a platform for predictive risk assessment, management of dysfunction, as well as a means to relate multiple spatial scales. Simulation-based investigation of cartilage comes with many challenges including both the computational burden and often insufficient availability of data for model development and validation. This review outlines recent modeling and simulation approaches to understand cartilage function from a mechanical systems perspective, and illustrates pathways to associate mechanics with biological function. Computational representations at single scales are provided from the body down to the microstructure, along with attempts to explore multiscale mechanisms of load sharing that dictate the mechanical environment of the cartilage and chondrocytes.

Validation of computational models in biomechanics

The topics of verification and validation have increasingly been discussed in the field of computational biomechanics, and many recent articles have applied these concepts in an attempt to build credibility for models of complex biological systems. Verification and validation are evolving techniques that, if used improperly, can lead to false conclusions about a system under study. In basic science, these erroneous conclusions may lead to failure of a subsequent hypothesis, but they can have more profound effects if the model is designed to predict patient outcomes. While several authors have reviewed verification and validation as they pertain to traditional solid and fluid mechanics, it is the intent of this paper to present them in the context of computational biomechanics. Specifically, the task of model validation will be discussed, with a focus on current techniques. It is hoped that this review will encourage investigators to engage and adopt the verification and validation process in an effort to increase peer acceptance of computational biomechanics models.

Computational modeling of ligament mechanics

This article provides a critical review of past and current techniques for the computational modeling of ligaments and tendons. A brief overview of relevant concepts from the fields of continuum mechanics and finite element analysis is provided. The structure and function of ligaments and tendons are reviewed in detail, with emphasis on the relationship of microstructural tissue features to the continuum mechanical hehavior. Experimental techniques for the material characterization of biological soft tissues are discussed. Past and current efforts related to the constitutive modeling of ligaments and tendons are classified by the particular technique and dimensionality. Applications of one-dimensional and three-dimensional constitutive models in the representation of the mechanical behavior of joints are presented. Future research directions are identified.

Strain in the human medial collateral ligament during valgus loading of the knee

The medial collateral ligament is one of the most frequently injured ligaments in the knee. Although the medial collateral ligament is known to provide a primary restraint to valgus and external rotations, details regarding its precise mechanical function are unknown. In this study, strain in the medial collateral ligament of eight knees from male cadavers was measured during valgus loading. A material testing machine was used to apply 10 cycles of varus and valgus rotation to limits of +/- 10.0 N-m at flexion angles of 0 degrees, 30 degrees, 60 degrees, and 90 degrees. A three-dimensional motion analysis system measured local tissue strain on the medial collateral ligament surface within 12 regions encompassing nearly the entire medial collateral ligament surface. Results indicated that strain is significantly different in different regions over the surface of the medial collateral ligament and that this distribution of strain changes with flexion angle and with the application of a valgus torque. Strain in the posterior and central portions of the medial collateral ligament generally decreased with increasing flexion angle, whereas strain in the anterior fibers remained relatively constant with changes in flexion angle. The highest strains in the medial collateral ligament were found at full extension on the posterior side of the medial collateral ligament near the femoral insertion. These data support clinical findings that suggest the femoral insertion is the most common location for medial collateral ligament injuries.

Strain transfer between a CPC coated strain gauge and cortical bone during bending

The finite element method was used to simulate strain transfer from bone to a calcium phosphate ceramic (CPC) coated strain gauge. The model was constructed using gross morphometric and histological measurements obtained from previous experimental studies. Material properties were assigned based on experiments and information from the literature. Boundary conditions simulated experimental cantilever loading of rat femora. The model was validated using analytical solutions based on the theory of elasticity as well as direct comparison to experimental data obtained in a separate study. The interface between the bone and strain gauge sensing surface consisted of layers of polysulfone, polysulfone/CPC, and CPC/bone. Parameter studies examined the effect of interface thickness and modulus, gauge geometry, partial gauge debonding, and waterproofing on the strain transfer from the bone to the gauge sensing element. Results demonstrated that interface thickness and modulus have a significant effect on strain transfer. Optimal strain transfer was achieved for an interface modulus of approximately 2 GPa. Strain transfer decreased consistently with increasing interface thickness. Debonding along the lateral edges of the gauge had little effect, while debonding proximal and distal to the sensing element decreased strain transfer. A waterproofing layer decreased strain transfer, and this effect was more pronounced as the modulus or thickness of the layer increased. Based on these simulations, specific recommendations were made to optimize strain transfer between bone and CPC coated gauges for experimental studies.

Simple shear testing of parallel-fibered planar soft tissues

The simple shear test may provide unique information regarding the material response of parallel-fibered soft tissues because it allows the elimination of the dominant fiber material response from the overall stresses. However, inhomogeneities in the strain field due to clamping and free edge effects have not been documented. The finite element method was used to study finite simple shear of simulated ligament material parallel to the fiber direction. The effects of aspect ratio, clamping prestrain, and bulk modulus were assessed using a transversely isotropic, hyperelastic material model. For certain geometries, there was a central area of uniform strain. An aspect ratio of 1:2 for the fiber to cross-fiber directions provided the largest region of uniform strain. The deformation was nearly isochoric for all bulk moduli indicating this test may be useful for isolating solid viscoelasticity from interstitial flow effects. Results suggest this test can be used to characterize the matrix properties for the type of materials examined in this study, and that planar measurements will suffice to characterize the strain. The test configuration may be useful for the study of matrix, fiber-matrix, and fiber-fiber material response in other types of parallel-fibered transversely isotropic soft tissues.

Unusual proton Zeeman spin relaxation in an organic solid: several crystal polymorphs or different glass structures?

Solid state proton Zeeman relaxation rate R1z measurements in two isomers of an organic solid (1- and 2-ethylnaphthalene) are reported. The samples are liquids at room temperature and the temperature T and Larmor frequency omega dependence of R1z depends strongly on how the sample is solidified. Methyl group (CH3) rotation is responsible for the proton spin relaxation and the methyl groups serve as probes of the local environment. The R1z measurements clearly distinguish between different solid states due to the differences in local structure at the several-molecule level. The experiments cannot be used to determine the states of these Van der Waals solids although interpreting the relaxation rate data suggests the states are unusual. We propose that these systems might exist in two (2-ethylnaphthalene) or more (1-ethylnaphthalene) polycrystalline polymorphs or that we are observing distinguishable glassy states, or, both. A phase transition is observed in 1-ethylnaphthalene. Variable temperature X-ray studies of organic systems that solidify well below room temperature are difficult, or at least not routine, and proton spin relaxation measurements serve as a convenient starting point for investigating such systems.

Reduced gap strains induce changes in bone regeneration during distraction

A bilateral New Zealand white rabbit model of distraction osteogenesis (DO) was used to investigate the relationship between strain environment and bone regeneration during limb lengthening. In seven (n = 7) rabbits, a stiffener was applied to the fixator on one side to reduce strains within the gap tissue after lengthening was completed. Animals were euthanized six days later and their distraction zones were harvested and analyzed for changes in new bone volume and architecture. Nonlinear finite element analyses (FEA) were performed to predict changes in the gap strain environment. FEA results predicted a nearly uniform sevenfold decrease in average strain measures within the distraction zone. No change in total average new bone volume and significant decreases in both bone volume fraction (BV/TV) and trabecular thickness (Tb.Th) were observed in tibiae in which gap strains were reduced experimentally, compared to contralateral controls. These results suggest that fixator stiffening influenced the architecture but not the amount of newly formed bone. This animal model of distraction might be used to study the mechanisms by which strain fields affect events in bone repair and regeneration, such as cell proliferation, precursor tissue differentiation, and altered growth factor and nutrient delivery to tissues.

Material characterization of human medial collateral ligament

The objectives of this study were to determine the longitudinal and transverse material properties of the human medial collateral ligament (MCL) and to evaluate the ability of three existing constitutive models to describe the material behavior of MCL. Uniaxial test specimens were punched from ten human cadaveric MCLs and tensile tested along and transverse to the collagen fiber direction. Using load and optical strain analysis information, the tangent modulus, tensile strength and ultimate strain were determined. The material coefficients for each constitutive model were determined using nonlinear regression. All specimens failed within the substance of the tissue. Specimens tested along the collagen fiber direction exhibited the typical nonlinear behavior reported for ligaments. This behavior was absent from the stress-strain curves of the transverse specimens. The average tensile strength, ultimate strain, and tangent modulus for the longitudinal specimens was 38.6 +/- 4.8 MPa, 17.1 +/- 1.5 percent, and 332.2 +/- 58.3 MPa, respectively. The average tensile strength, ultimate strain, and tangent modulus for the transverse specimens was 1.7 +/- 0.5 MPa, 11.7 +/- 0.9 percent, and 11.0 +/- 3.6 MPa, respectively. All three constitutive models described the longitudinal behavior of the ligament equally well. However, the ability of the models to describe the transverse behavior of the ligament varied.

Bone regeneration and fracture healing. Experience with distraction osteogenesis model

The relation between physical forces and the processes of bone regeneration and healing remains incompletely understood. Gaps in understanding of these processes stem in part from models that produce inadequate amounts of new bone for study. Bone created through the use of distraction osteogenesis provides an attractive substrate for the study of mechanical forces and their effects on bone formation because this technique produces large volumes of new bone in a controlled fashion. The optimal mechanical environment in which bone formation occurs clinically has not been fully determined. In laboratory studies, however, the mechanical environment can be manipulated, and resultant changes in bone formation can be measured. To investigate how changes in strain environment influence patterns of bone formation, a bilateral New Zealand White rabbit model of bilateral distraction osteogensis was implemented. When a stiffener was applied to the external distractor, computation analyses predicted a sevenfold to eightfold decrease in all strain measures. These reductions in gap strains appeared to induce significant decreases in bone volume fraction and mean trabecular thickness. When osteotomies were created at a 30 degrees angle to the bony axis to generate more shear within the gap tissue, changes in the distribution of gap strains and resultant new bone architecture were observed. Specific correlations between changes in tissue level strains and the pattern of bone regeneration were seen in both experiments. These results provide direct in vivo evidence that pluripotential gap tissues are sensitive to their physical surroundings. Mechanisms responsible for this sensitivity might include vascularity, stem cell supply, and scaffolding architecture. The process of bone formation in distraction osteogenesis appears to be related to bone formation processes associated with more common conditions. The distraction osteogenesis model described suggests a mechanism for bone formation that seems applicable to other more common processes associated with bone formation, including fracture healing and impaired fracture healing.

Finite element implementation of anisotropic quasi-linear viscoelasticity using a discrete spectrum approximation

The objective of this work was to develop a theoretical and computational framework to apply the finite element method to anisotropic, viscoelastic soft tissues. The quasilinear viscoelastic (QLV) theory provided the basis for the development. To allow efficient and easy computational implementation, a discrete spectrum approximation was developed for the QLV relaxation function. This approximation provided a graphic means to fit experimental data with an exponential series. A transversely isotropic hyperelastic material model developed for ligaments and tendons was used for the elastic response. The viscoelastic material model was implemented in a general-purpose, nonlinear finite element program. Test problems were analyzed to assess the performance of the discrete spectrum approximation and the accuracy of the finite element implementation. Results indicated that the formulation can reproduce the anisotropy and time-dependent material behavior observed in soft tissues. Application of the formulation to the analysis of the human femur-medial collateral ligament-tibia complex demonstrated the ability of the formulation to analyze large three-dimensional problems in the mechanics of biological joints.

Two-wave mixing of focused Gaussian beams in photorefractive waveguides

We report two-wave mixing measurements in ion-implanted KNbO(3) planar waveguides and their numerical analysis in the framework of a two-dimensional model that takes the lateral intensity distribution of the two beams into account. We demonstrate that the gain and its time response can be interpreted in terms of an apparent interaction length and a spatially varying time constant.

Syntenic assignment of human chromosome 1 homologous loci in the bovine

Three mouse chromosomes (MMU 1, 3, and 4) carry homologs of human chromosome 1 (HSA 1) genes. A similar situation is found in the bovine, where five bovine chromosomes (BTA 2, 3, 5, 16, and unassigned syntenic group U25) contain homologs of HSA 1 loci. To evaluate further the syntenic relationship of HSA 1 homologs in cattle, 10 loci have been physically mapped through segregation analysis in bovine-rodent hybrid somatic cells. These loci, chosen for their location on HSA 1, are antithrombin 3 (AT3), renin (REN), complement component receptor 2 (CR2), phosphofructokinase muscle type (PFKM), Gardner-Rasheed feline sarcoma viral (v-fgr) oncogene homolog (FGR), alpha fucosidase (FUCA1), G-protein beta 1 subunit (GNB1), alpha 1A amylase, (AMY1), the neuroblastoma RAS viral (v-ras) oncogene homolog (NRAS), and alpha skeletal actin (ACTA1). AT3, REN, CR2, and GNB1 mapped to BTA 16, PFKM to BTA 5, AMY1A and NRAS to BTA 3, FGR and FUCA1 to BTA 2, and ACTA1 to BTA 28.

Soft tissue fixation to bone. A biomechanical analysis of spiked washers

The initial fixation strengths of two spiked-washer designs were evaluated using human femurs and fascia lata tissue. Fascia lata was attached to the femur using the fixation devices, and then each femur-washer-fascia lata complex was loaded in tension to failure. Load-elongation curves were recorded, the initial failure load, initial failure displacement, stiffness, ultimate load, and ultimate displacement were determined for each test, and failure modes were recorded. Results indicated that the 6-spike design provided superior initial fixation strength in the 19-mm diameter size. This washer design was then compared with two commercially available fixation devices: the spiked AO washer and soft tissue fixation plate. Fixation provided by the prototypal washer design was not different in most instances from that provided by the AO fixation devices. Based on these results, important design characteristics for soft tissue spiked washers are identified and discussed.

Healing of the medial collateral ligament following a triad injury: a biomechanical and histological study of the knee in rabbits

The effect of a partial medial meniscectomy and anterior cruciate ligament (ACL) transection on medial collateral ligament (MCL) healing was studied in skeletally mature rabbits. Two groups of animals, group I (isolated MCL rupture) and group II (MCL rupture with ACL transection and partial medial meniscectomy), were examined. At 6 and 12 weeks postoperatively, histological examination of the healing MCL and biomechanical evaluation of the varus-valgus (V-V) knee rotation and tensile properties of the femur-MCL-tibia complex (FMTC) were performed. Group II animals experienced substantial joint degeneration by 6 weeks. Progressive osteophyte formation was observed adjacent to the MCL insertions along with proximal migration of the MCL tibial insertion between 6 and 12 weeks. Histologic examination of the healing MCL substance from both groups showed disorganized collagen, inflammation, and fibroblast proliferation that decreased over time. For group II knees, the V-V knee rotation was found to be significantly elevated (4.7 to 5.2 times the contralateral control), and did not decrease with time. In contrast, the V-V knee rotations of the group I specimens were 1.8 times greater than control immediately following injury, and approached control values by 12 weeks. Tensile testing of the FMTCs revealed that the ultimate load increased with time for both groups, but group I had significantly higher values than group II. The linear stiffness in group I was not different than that group II and did not increase with time. For the mechanical (material) properties of the healed MCL substance, the modulus of the healing tissue for group II was only 40% that of group I. The structural properties of the FMTC and the mechanical properties of the MCL substance from both groups at 6 and 12 weeks were significantly different from the contralateral controls. We further demonstrated that immediately after ACL reconstruction, the V-V rotation of group II knees could be restored to group I levels. Recent clinical studies of MCL healing following isolated complete ligament tears have suggested that nonoperative management without immobilization leads to excellent treatment outcome. However, in more severe injuries involving additional tissues, poor quality of the healed ligament tissue and articular degeneration are observed. Our results demonstrate the deleterious effects of an untreated triad injury on the healing of the MCL substance and its insertions. Examination of the MCL substance suggests that a much larger healing mass is formed following a triad injury, which partially compensates for inferior ligament mechanical properties.(ABSTRACT TRUNCATED AT 400 WORDS)

Evaluation of a new injury model to study medial collateral ligament healing: primary repair versus nonoperative treatment

The medial collateral ligament (MCL) of the rabbit left hindlimb was ruptured by a rod placed beneath it, resulting in a "mop-end" tear of the ligament substance with simultaneous injury to the insertion sites. Using this model, we compared primary ligament repair and nonoperative treatment using biomechanical and histologic techniques at time zero, 10 days, and 6 and 12 weeks postoperatively. Biomechanical evaluation included measurement of varus-valgus (V-V) knee rotation, in situ load on the MCL, and tensile testing of the femur-MCL-tibia complex (FMTC). The V-V rotation of all experimental knees decreased over time. At 12 weeks, V-V rotation of experimental knees was still 1.3 times larger than that of controls. Primary repair initially decreased V-V rotation, but at 6 and 12 weeks there was no statistical difference between operated and nonoperated knees. The in situ load on the MCL followed the same trends. There was no significant effect of MCL repair on any of the tensile properties. However, postoperative healing time significantly improved the FMTC structural properties in both experimental groups. Failure modes of the FMTCs and histologic sections of the ligament insertion sites indicated that after injury the ligament insertion to bone recovered more slowly than the ligament substance. Tensile testing of the FMTC showed that even at 12 weeks postoperatively the mechanical properties of the healed ligament material remained significantly different from those of the controls.

Aging and sex-related changes in the biomechanical properties of the rabbit medial collateral ligament

The effects of aging and sex on the tensile properties of the rabbit medial collateral ligament (MCL) were examined. The femur-MCL-tibia complex (FMTC) of male and female rabbits, of representative ages before and after epiphyseal closure up to the onset of senescence (i.e., 3.5, 6, 12 and 36 months of age) were examined. A group of 48-month-old female rabbits was also tested. The specimens were tensile tested to failure in order to obtain both the load-elongation curve of the FMTC (structural properties) and the stress-strain curve of the MCL substance (mechanical properties). Significant increases in the linear stiffness, ultimate load and energy absorbed at failure of the FMTC were noted in both the males and females during skeletal maturation, but the FMTCs of the older rabbits began to show a slight decrease in these properties. The ultimate load of the FMTC for the male rabbits reached its plateau at approximately 6 months of age, while that of the females did not plateau until 12 months of age. The modes of failure correlated well with closure of the epiphyses in both sexes, i.e., tibial avulsion failure for the skeletally immature groups and mid-substance for the skeletally mature groups. The modulus of the MCL substance increased during maturation for both sexes until 12 months, and then gradually declined until 48 months. The tensile strength remained relatively constant after 12 months of age but was slightly reduced at 48 months for the females. Thus, the rate of skeletal maturation contributed in part to the differences in the tensile properties of both the male and female rabbits.

Measurement of changes in ligament tension with knee motion and skeletal maturation

This study was designed to determine the in situ strains, stresses, and loads in the medial collateral ligament (MCL) of skeletally immature and mature rabbits. Using a noncontact method, the magnitudes of the in situ strains were first determined as a function of knee flexion angle. The MCL was divided into three anatomical regions (anterior, middle, and posterior) across its width. For strain measurements, the variation of a gauge length in these regions was obtained in the intact knee at 60, 90, and 120 deg of flexion. Subsequently, all soft tissues around the knee were dissected away, leaving the femur-MCL-tibia (FMT) complex. The MCL was allowed to retract freely and the new length, called the zero length, was measured. From this, the in situ strains were determined. To obtain the stress-strain relationship of the FMT complex, the specimens were subjected to tensile testing. Knowing the in situ strains and the stress-strain relationship, the in situ stresses in the three anatomical regions of the MCL were determined as a function of knee flexion angle. Multiplying these stresses by 1/3 of the cross-sectional area and summing the loads thus calculated, the in situ loads of the MCL were obtained. Our data suggest that the in situ load in the MCL is not large within the range of knee flexion angles studied, i.e., 1.4 to 2.7 N for the skeletally immature animals and 3.0 to 5.8 N for the skeletally mature animals. An increase in the in situ load with skeletal maturation was demonstrated.

Ideas and inducements in mental health policy

Between 1946 and 1963, federal officials sought to change the national practice of providing mental health care, away from state-run mental institutions and toward outpatient care based in local communities. These policy makers relied on two policy instruments, ideas and inducements. Both instruments contributed to unexpectedly significant changes in federal, state, and local policy. I conclude that a policy instrument framework helps to disentangle the strands of successful public management, and that it is useful to think of ideas as policy instruments that offer leverage on policy outcomes.

Correlation of 1a afferent conduction with the ataxia of Fisher syndrome

The pathophysiology of the ataxia in Fisher syndrome (the syndrome of acute ophthalmoplegia, ataxia, and areflexia) has been attributed to both peripheral nervous system pathology and cerebellar system dysfunction. Pathologic studies have demonstrated no consistent central nervous system abnormalities. We present a case in which abnormalities of 1a sensory conduction were found to correlate directly with the degree of ataxia, without impairment of motor or cutaneous sensory conduction. We propose that the ataxia seen in typical Fisher syndrome may be due to demyelination of 1a afferent fibers.

Substance vs. symbol in administrative reform: the case of human services coordination

In recent years the most popular strategy of reform in the human services arena has been to foster coordination among agencies serving the same populations. The certainty of difficulties in implementing coordination programs and the uncertainty of achieving improvements in service delivery have not dimmed the enthusiasm among policymakers for these programs. This persistent popularity seems to be rooted in the strong symbolic appeal of "coordination," which has overridden attention to evidence about performance.

Rapid method for auxotyping multiple strains of Neisseria gonorrhoeae

A rapid method for auxotyping strains was developed that uses microtiter plates. This miniplate technique enables rapid identification of major auxotypes present in clinical strains. Additional growth requirements can be identified by adding individual amino acid supplements to complete gonococcal genetic medium. Analysis of 8 clones from 40 patients revealed that 10 had more than 1 auxotype. Deoxyribonucleic acid-mediated transformation can be used to establish whether the strains with apparently more than one auxotype are defective in the same locus in each of the involved biosynthetic pathways. Selection of more than one clone is required in precise epidemiological studies.