The Effects of Anterior Cruciate Ligament Thickness, Knee Joint Laxity, Activity Level, Neuromuscular Imbalances and Lower Extremity Muscular Activation Patterns on Anterior Cruciate Ligament Loading

There are numerous known mechanisms of anterior cruciate ligament (ACL) injury risk that span from knee joint laxity to landing mechanics. However, the relationship of these mechanisms to ACL loading during landing is unclear. In addition to landing mechanics, anthropological aspects such as ACL diameter, which can now be obtained via ultrasound, may also be an important mechanism for ACL loading. However, the relationship between ACL diameter to ACL loading and landing mechanics remains unknown. This study was conducted with three primary purposes. The first purpose of this study was to examine the inter and intra-rater reliability of using ultrasound to measure the diameter of the full ACL and anteromedial bundle of the ACL. The second purpose was to examine the relationship between the anteromedial bundle diameter and lower extremity strength, whole body anthropometrics, and previous physical activity levels. The third purpose was to examine the relationship between simulated ACL loading and pre-activation electromyography of lower extremity muscles, anteromedial bundle diameter and knee joint laxity. Two separate raters with differing levels of experience (low: Rater 1 and moderate: Rater 2) used diagnostic ultrasound to image bilateral ACLs of twenty participants. Rater 1 also performed an additional imaging session with the same population. Interclass correlations were conducted to examine 1) intra-rater reliability between sessions for Rater 1 and 2) inter-rater reliability between the Raters 1 and 2. To address the second purpose of this study, anteromedial bundle diameter, height, weight, strength measurements of the knee flexors, knee extensors, hip abductors, and hip adductors and previous physical activity were recorded for 17 participants. Pearson product correlations were conducted between anteromedial bundle diameter and the recorded variables. To address the third purpose of this study, 17 participants\u27 pre-activation of lower extremity muscles, anteromedial bundle diameter and passive knee joint laxity were recorded. Next, participants performed single leg landings from a 40 cm height and a height equal to their maximal jumping capabilities. During landings, three dimensional kinematic and kinetic variables were recorded as well as electromyography (EMG) of the Rectus Femoris, Vastus Medialis, Vastus Lateralis, Medial Hamstring, Lateral Hamstring, Medial Gastrocnemius, and Gluteus Medius. Participant specific musculoskeletal models were generated for each participant. Three dimensional ACL loading was calculated using previously established equations. Pearson product correlations were then utilized to analyze the relationship of ACL loading to knee joint laxity, anteromedial bundle diameter and pre-activation of the lower extremity muscles. Moderate correlations were found for inter and intra-rater reliabilities. There were weak correlations found for the full ACL diameter during inter and intra-rater analyses. The current results show that the anteromedial bundle can be found and measured more reliably than the full ACL. There were no significant correlations between anteromedial bundle diameter and previous exercise activity levels. However, significant correlations were found with quadriceps and adductor strength values. Simulated ACL loading was only found to have significant correlations with lateral hamstring pre-activation for both 40 cm and relative drop landing heights. The current results suggest that the pre-activation of the hamstrings may influence ACL loading if the medial and lateral hamstring groups are activated disproportionately. The results from these studies establish that the anteromedial bundle can be analyzed with moderate reliability from researchers utilizing ultrasound. Future research involving diagnostic ultrasound should consider analyzing the anteromedial bundle to increase reliability and generalizability of their results. Although it may be possible for stressors to cause hypertrophy in the ACL, few factors known to stress the ACL are significantly associated with the size of the anteromedial bundle diameter. Thus, the association between those mechanisms and ACL loading may not be as clear

An assessment of stream fish vulnerability and an evaluation of conservation networks in Missouri

Stream fish species in Missouri are being exposed to habitat degradation, as well as increases in stream temperature and alterations to the flow regime due to climate change. These threats are likely to have negative consequences on aquatic biodiversity. In order to conserve these species it is important to determine which species are the most vulnerable, and to identify where the best opportunities for conservation and management exist. Two indices to assess stream fish vulnerability were developed and compared. Both indices accounted for species tolerance of habitat degradation, warming stream temperatures, and alterations to the flow regime, as well as factors such as dispersal ability, range size, rarity, and the level of fragmentation of the species habitat. One index used measured species responses to assess environmental tolerances, while the other used trait associations. Species exhibited a range of vulnerabilities, and differences were observed based on whether traits or measured responses were used. A systematic conservation planning tool was used to identify the best areas for stream fish conservation within and complementary to Missouri�s conservation networks. Valuable areas were identified across the state, but the majority of high value stream segments were located in the Ozarks subregion. In addition to providing information to aid in the management and conservation of Missouri�s stream species, these frameworks for assessing stream fish vulnerability and prioritizing stream conservation could be adapted for use in other regions

Perfect coupling of light to surface plasmons with ultra-narrow linewidths

We examine the coupling of electromagnetic waves incident normal to a thin silver film that forms an oscillatory grating embedded between two otherwise uniform, semi-infinite half spaces. Two grating structures are considered, in one of which the mid point of the Ag film remains fixed whereas the thickness varies sinusoidally, while in the other the mid point oscillates sinusoidally whereas the film thicknesses remains fixed. On reducing the light wavelength from the long wavelength limit, we encounter signatures in the transmission, T, and reflection, R, coefficients associated with: i) the short-range surface plasmon mode, ii) the long-range surface plasmon mode, and iii) electromagnetic diffraction tangent to the grating. The first two features can be regarded as generalized (plasmon) Wood's anomalies whereas the third is the first-order conventional (electromagnetic) Wood's anomaly. The energy density at the film surface is enhanced for wavelengths corresponding to these three anomalies, particularly for the long range plasmon mode in thin films. When exciting the silver film with a pair of waves incident from opposite directions, we find that by adjusting the grating oscillation amplitude and fixing the relative phase of the incoming waves to be even or odd, T+R can be made to vanish for one or the other of the plasmon modes; this corresponds to perfect coupling (impedance matching in the language of electrical engineering) between the incoming light and these modes.Comment: 13 pages, 5 figures. accepted J. Chem. Phy

Beyond relevance--characteristics of key papers for clinicians: an exploratory study in an academic setting

pre-printObjective: The purpose of this study was to determine what factors beyond relevance influence a clinician's decision to choose to read one journal article over another in satisfying an information need. Design: Seventeen health care providers were interviewed and then surveyed regarding the characteristics of key articles (those they would not want to miss). On a Likert scale, the clinicians graded forty-two characteristics for importance in the decision process. Relevance was assumed and not at issue. Setting: The study took place in an academic health sciences center. Subjects: The subjects were seventeen clinicians, all with patient care responsibilities. There were four internists, four surgeons, three family practitioners, three pediatricians, two psychiatrists, and one clinical psychologist. Results: Factors beyond relevance that most often influenced the decision process pertained to methodological rigor, authors and their institutional affiliations, document types, and population studied. Conclusions: Among the clinicians surveyed, factors beyond topicality influenced judgments as to what constitutes an important article. The emphasis respondents gave to certain attributes is echoed in other published work and highlights the need for more intensive investigation of these non-subject indicators as search parameters. Improved searching capabilities might well lead to a significant reduction in the clinician's information overload

The Missouri planning grant for the education and training of health sciences librarians

pre-printThe planning grant at the School of Library and Informational Science (SLIS) at the University of Missouri has two aims: (a) developing a model curriculum for health sciences librarianship at the master's level and (b) developing materials that can be delivered by alternative instructional methods. To accomplish the first aim, the faculty will investigate the possibility of offering courses in other disciplines, such as health care administration, educational technology, adult education, and medical sociology. In addition, the SLIS faculty will investigate the development of new kinds of placement for the students' practicum experience. To reach the second aim, the SLIS faculty will investigate alternative means of delivering both graduate and continuing education. Three instructional modalities will be evaluated. Some material will be delivered via satellite broadcast, some material will be made available via the World Wide Web and some will be presented in an intensive seminar. The outcome of the planning grant will be two distinct plans. The first will be a plan for the curriculum in health sciences librarianship at the master's level. The second will be a plan for offering instruction through alternative methods, both for graduate education and for continuing education

Retrieval from full-text medical literature: the dream & the reality

pre-printWhile the retrieval of the full-text of a document might seem to end all the hassle of using traditional retrieval systems, the results of the MEDLINE/Full-Text Project indicate that retrieval from the current full-text databases of biomedical journal literature does not match the dream. During the first phase of the project the researchers learned that searching the full-text databases resulted in the retrieval of a significantly larger number of relevant documents than MEDLINE. However, the full-text databases also resulted in a large number of non-relevant documents. Currently the researchers are focusing on how to search these databases to continue retrieving the large number of relevant documents but without so many non-relevant items

Regulation of mRNA Export by the PI3 kinase / AKT Signal Transduction Pathway

UAP56, ALY/REF, and NXF1 are mRNA export factors that sequentially bind at the 5\u27 end of a nuclear mRNA, but are also reported to associate with the Exon Junction Complex (EJC). To screen for signal transduction pathways regulating mRNA export complex assembly we used Fluorescence Recovery after Photobleaching (FRAP) to measure the binding of mRNA export and EJC core proteins in nuclear complexes. The fraction of UAP56, ALY/REF, and NXF1 tightly bound in complexes was reduced by drug inhibition of the PI3 kinase / AKT pathway, as was the tightly bound fraction of the core EJC proteins eIF4A3, MAGOH, and Y14. Inhibition of the mTOR mTORC1 pathway decreased the tight binding of MAGOH. Inhibition of the PI3 Kinase/AKT pathway increased the export of poly(A) RNA and of a subset of candidate mRNAs. A similar effect of PI3 kinase/AKT inhibition was observed for mRNAs from both intron-containing and intron-less Histone genes. However, the nuclear export of mRNAs coding for proteins targeted to the Endoplasmic Reticulum or to Mitochondria was not affected by the PI3 kinase/AKT pathway. These results show that the active PI3 kinase/AKT pathway can regulate mRNA export and can promote the nuclear retention of some mRNAs

Effects of Gait Speed of Femoroacetabular Joint Forces

Alterations in hip joint loading have been associated with diseases such as arthritis and osteoporosis. Understanding the relationship between gait speed and hip joint loading in healthy hips may illuminate changes in gait mechanics as walking speed deviates from preferred. The purpose of this study was to quantify hip joint loading during the gait cycle and identify differences with varying speed using musculo skeletal modeling. Ten, healthy, physically active individuals performed walking trials at their preferred speed, 10% faster, and 10% slower. Kinematic, kinetic, and electromyographic data were collected and used to estimate hip joint force via a musculoskeletal model. Vertical ground reaction forces, hip joint force planar components, and the resultant hip joint force were compared between speeds. There were significant increases in vertical ground reaction forces and hip joint forces as walking speed increased. Furthermore, the musculoskeletal modeling approach employed yielded hip joint forces that were comparable to previous simulation studies and in vivo measurements and was able to detect changes in hip loading due to small deviations in gait speed. Applying this approach to pathological and aging populations could identify specific areas within the gait cycle where force discrepancies may occur which could help focus management of care

Wearing Knee Sleeves During Back Squats Does Not Improve Mass Lifted or Affect Knee Biomechanics

Purpose:Knee sleeves have become widely popular in the exercise realm, especially for knee support during back squats. Knee sleeves are successful in providing frontal plane knee support during functional tasks, but have not been investigated in back squats. Knee wraps, a somewhat similar elastic material, provide elastic energy that increases weight lifted during back squats. Thus, it is possible the thick neoprene knee sleeves could prove advantageous for back squats. The purpose of this study was to examine the effects of knee sleeves on weight lifted, knee biomechanics, and muscle activations during back squats.Methods:Fifteen resistance trained men and women performed 1-repetition maximum (1-RM) squats to full depth and 80% 1-RM to full and parallel depths during two separate randomized sessions: with/without knee sleeves. Three-dimensional motion capture, force platforms, and electromyography recorded knee biomechanics and activations of the rectus femoris, vastus medialis, biceps femoris long head, and gluteus maximus during all squats.Results:Maximal weight lifted did not improve when using knee sleeves. Frontal plane knee biomechanics did not differ for 1-RM or submaximal squats to either depth between conditions. Knee external rotation moments during descent were larger with sleeves during submaximal squats. Reduced integrated ascent phase gluteus maximus activations occurred during both 1-RM and submaximal squats with knee sleeves.Conclusions:The results of this study show that wearing knee sleeves does not provide additive effects to weight lifted and do not appear to alter frontal plane mechanics during weighted back squats